Archive for the ‘Pools’ Category

After the Hurricane: How to Handle a Flooded Swimming Pool or Spa

Friday, October 20th, 2017

flooded-poolThe 2017 hurricane season is one for the record books. Among the issues residents in affected areas are contending with is flooded backyard swimming pools and spas. A new Fact Sheet from The Association of Pool & Spa Professionals provides expert and detailed guidance on safely returning your flooded pool or spa to working condition. This article lists key highlights from the Fact Sheet, but we advise you to consult the original document for the most detailed guidance.

Electrical Safety

Safety is the first and most important consideration in addressing your flooded pool or spa. Electrocution is “a real and present danger and frequently accounts for many deaths after a major storm,” according to the Fact Sheet. Before attempting any clean-up activities, turn off the power to all pool and spa equipment at the main circuit breaker or fuse box. Remember: Never touch a circuit breaker or fuse with wet hands or while standing on a wet surface or in standing water.

Floodwaters and their contaminants can damage the motors of pool and spa pumps. A licensed electrician can assist in assessing electrical damage, and only a licensed professional should perform electrical repair work such as replacing electrical components. As the Fact Sheet notes, “Remediating electrical equipment is not a do-it-yourself project.”

Water Quality

Assume that your flooded pool or spa is contaminated with chemicals, fertilizers, oils, gasoline, sewage, pathogens, silt and debris. Do not use the pool or spa or permit pets to enter the pool. Pool water that has become murky with algae and debris is particularly dangerous because limited visibility through the water from the pool deck could obscure anyone present and in distress. Keep small children away from the pool by installing a temporary safety fence around the pool. This will also help prevent individuals from accidentally tripping over storm debris and into the pool. If wildlife, such as snakes or alligators, have taken up residence in the pool, contact your local animal control or wildlife management authority for help with removal. Mosquitoes that can transmit illnesses such as Zika virus, West Nile virus and dengue fever may be breeding in the standing water of your pool or spa—another reason to get your pool back in working order, with an appropriate chlorine residual level, as soon as possible. For flooded pools supporting mosquito larvae, if the time to corrective cleaning is delayed past a week or longer, mosquito larvaecide “dunks” or pellets can be used to destroy larvae.

According to the Fact Sheet, after hurricane rainfall or a storm surge, it is neither practical nor cost effective to determine the types and/or amounts of toxic contaminants in the water for potential treatment. The experts recommend that the pool or spa water be drained, all plumbing lines purged, and filter media replaced before refilling the pool. This advice comes with the important warning that once drained, high groundwater can cause an in-ground pool to “pop” out of the ground due to hydrostatic pressure, causing severe structural damage. Once again, a licensed pool professional can chart the best course of action for draining, including properly disposing of the contaminated water.

Once drained, the pool or spa can be cleaned of all debris and floor and side surfaces cleaned with 10% muriatic acid (hydrochloric acid) solution or a solution of liquid chlorine bleach1. Never mix chlorine and acid solutions together, as toxic chlorine gas will be produced! Rinse surfaces thoroughly after cleaning, and remove rinse water before refilling the pool or spa with clean, potable water. Balance and sanitize pool or spa water before permitting users to enter and enjoy your pool or spa once again.

What about Pool and Spa Chemicals?

Pool and spa chemicals that have gotten wet, contaminated or mixed with other chemicals in an uncontrolled manner are potentially dangerous. Violent chemical reactions, including explosions, fire and toxic fume releases are possible, according to the Fact Sheet. Pool and spa chemical concerns should be addressed first to your local fire department, as they may have to respond in person. Additionally, CHEMTREC is a “24/7” emergency call center that provides immediate information and assistance to anyone involved in a chemical or hazardous material incident around the globe. A call to CHEMTREC at 1-800-424-9300 is free of charge.

To help prevent future hazards, store pool and spa chemicals in a cool, dry location (away from children, the elements, and food), with incompatible chemicals, such as chlorine products and acid, well separated. Store liquid chemicals on the lowest shelf to avoid accidental mixing in the event of leakage.

Pools and spas may not be the first priority for residents in hurricane recovery, but they are important from a health and safety perspective. We commend APSP for its helpful and timely Fact Sheet addressing flooded swimming pools and spas.

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1 To 1 gallon of water, add ¼ cup of 3.5% sodium hypochlorite bleach, or 7 teaspoons of standard (6.0% sodium hypochlorite bleach), or 5 teaspoons of 8.25% sodium hypochlorite bleach.

In the Wake of Hurricanes: The Problem with Standing Water

Friday, September 15th, 2017
A discarded tire containing standing water can become a choice breeding ground for mosquitoes.

A discarded tire containing standing water can become a choice breeding ground for mosquitoes.

As flood waters recede in Houston and Florida, a new public health threat rears its ugly head: Mosquitoes breeding in standing water left in the wake of hurricanes. Puddles, flower pots and saucers, rain barrels, bird baths, pet bowls, discarded tires, overturned trash can lids, canvas and plastic tarps covering boats and pools, and even swimming pools themselves can become watery incubators for mosquitoes.

Although most mosquitoes do not spread disease, some do spread Zika virus, West Nile virus, chikungunya, malaria, encephalitis and dengue fever. Fortunately, after a quiet summer for Zika virus on the US mainland during which there was no known local transmission of the virus, the US Centers for Disease Control and Prevention (CDC) does not expect to see cases of Zika virus appearing in the wake of flooding from the recent hurricanes, even though mosquito populations are expected to increase.

Operation Repopulation for People … and Mosquitoes

Humans returning to waterlogged homes in the Houston area and Florida are not alone in rebuilding their “habitats.” Although the torrential rains and high winds of hurricanes typically wash out mosquito breeding sites, the insects always return to reclaim their habitats, made all the more inviting by stagnant flood water. How quickly will they reappear? The mosquito lifecycle, from egg to larvae to pupa to adult, can range from four days to as long as one month, according to the US Environmental Protection Agency (EPA).  

Tips for Reducing Standing Water in and around Your Home1

Avoiding Mosquito Bites

Besides removing standing water, shore up your personal defenses against mosquitoes by using a CDC-approved insecticide, such as DEET, picaridin, IR3535, oil of lemon eucalyptus, or para-menthane-diol. Lightweight, light colored and loose-fitting long-sleeved shirts and long pants also can help protect you from mosquito bites when working outdoors.
  • As much as possible, eliminate objects on your property that can collect and hold even small volumes of water.
  • Empty, scrub and change the water in bird baths at least once a week. Scrubbing is needed to remove mosquito eggs, which firmly attach themselves to hard surfaces.
  • Assure that water can drain out of recycling containers, drilling holes in the bottom of them if needed.
  • Repair leaky outdoor faucets.
  • Stock ornamental pools with predacious minnows, which eat mosquito larvae, or treat with “biorational larvicides,” purchased in hardware stores.
  • Keep backyard pools properly chlorinated.
  • Empty and dry the water from small inflatable and molded plastic kiddie pools immediately after use.
  • Remove leaves and other debris from rain gutters and drains.
  • Ensure window and door screens are in good repair.
  • Eliminate seepage from cisterns, cesspools and septic tanks.
  • Fill or drain puddles, ditches and swampy areas.
  • Plug tree holes (see this EPA website).
  • If it is necessary to reside in hurricane damaged homes that allow easy entry for mosquitoes, utilize mosquito nets while sleeping.

After the destruction wreaked by Hurricanes Harvey and Irma, standing water represents a less dramatic, but insidious challenge for many who have already endured much hardship. We hope these tips will prove useful in the recovery of our neighbors in hurricane-affected communities.

Fred M. Reiff, P.E., is a retired official from both the U.S. Public Health Service and the Pan American Health Organization, and lives in the Reno, Nevada area.

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1For more detailed tips and information, please see the website of the American Mosquito Control Association.

Pool Chemical Safety: There’s No Substitute for Vigilance

Friday, July 7th, 2017

Pool Chemical SafetyWe could not safely enjoy a refreshing dip in the pool this summer without someone shouldering the responsibility of using and storing pool chemicals correctly. Someone has to apply and store the chemicals that keep pool water sanitized and so clear that a swimmer floundering in deep water is visible to life guards. Pool chemical safety is the responsibility of backyard pool owners, professional pool service providers, community pool managers and life guards. It’s one of those usually “invisible” jobs that may be noticed only when something goes wrong.

Why Pool Chemicals?

Swimming pools are essentially communal bath tubs. Pool chemicals are necessary to help maintain appropriate pool water quality. That is especially true when patrons neglect the standard advice to shower before swimming. Knowing that each swimmer who enters the water without first showering brings with them about 0.14 grams of fecal matter adhering to the perianal area, the potential for exposure to disease-causing germs in the water becomes intuitively obvious.

Pool disinfectants are added to destroy pathogens (disease-causing germs) that could be ingested by swallowing even a small amount of water. Other chemicals help control the pH of the water to maximize the effectiveness of disinfectants. Chlorine-based disinfectants, for example, are effective at destroying a wide range of pathogens in pool water when pool testing strips indicate a “free chlorine” level between 1 and 3 parts per million and pH between 7.2 and 7.8. Swimming pools would become nasty “petri dishes” without appropriate water disinfection.

Pool Chemical Mishaps

According to a 2014 CDC report1, in 2012, an estimated 4,876 people visited an emergency department for injuries associated with pool chemicals. Nearly half of these were younger than 18 years old, and the most common diagnosis was poisoning by inhalation of vapors, fumes or gases. The CDC report includes a description of a 2013 incident in Minnesota in which seven children and one adult were taken to emergency departments after being in a pool in which both the chlorine level and the pH exceeded state limits. The study cites several issues that may have caused or contributed to the event, including a failure of the facility’s automated chemical feed and monitoring system as well as a failure of pool operators to check equipment and pool chemistry. There is no substitute for vigilance when it comes to monitoring pool chemistry.

Pool chemical handlers and others can be injured when critical safety rules for storing and using pool chemicals are ignored. Inhaling fumes when opening pool chemical containers, mixing pool chemicals, attempting to pre-dissolve pool chemicals, and accidentally splashing chemicals in the eyes are some common mistakes. Other mistakes may not be immediately obvious, for example inadvertently spilling a cola-type soft drink near chemicals in the storage area could set off a dangerous chemical reaction that puts people at risk. That is why one of the rules of safe pool chemical storage is to refrain from bringing food or drink into the storage area. Another “recipe for disaster” is storing liquid chemicals above bags of solid chemicals; in the event that the container of liquid chemical leaks onto the bagged chemical, an unwanted chemical reaction could occur that endangers the health of pool staff and patrons. That is why it is important to store liquid chemicals securely in the lowest location.

Free Pool Chemical Safety Resources

CDC offers a pair of free, laminated pool chemical safety posters that are available in English or Spanish. The posters list important guidelines for safely using and storing pool chemicals. Another free resource is the online and smart phone-friendly Pool Chemical Safety video. The video, which illustrates many of the do’s and don’ts of safe pool chemical management, was developed by the American Chemistry Council and The Chlorine Institute. Please help promote these tools to the pool chemical handlers you know. If you are swimming in a healthy pool, you have them to thank.

Chris Wiant, M.P.H, Ph.D., is president and CEO of the Caring for Colorado Foundation.  He is also chair of the Water Quality & Health Council and a member of the National Drinking Water Advisory Council.

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195% confidence interval [CI] = 2,821–6,930

Zika Virus: What Can We Expect this Summer?

Friday, June 2nd, 2017
Mosquito repellent can help reduce exposure to mosquitoes that carry Zika virus; infants younger than two months can be protected with mosquito netting.

Mosquito repellent can help reduce exposure to mosquitoes that carry Zika virus; infants younger than two months can be protected with mosquito netting.

As summertime approaches and vulnerable areas of the US warm up, concerns over the potential spread of Zika virus are on the rise. The virus is spread mainly through the bite of an infected Aedes aegypti mosquito, but also can be transmitted sexually. Zika virus is associated with birth defects (microcephaly) in infants of infected mothers and Guillain-Barre Syndrome, an immune system disorder.

Last summer, several regions of the US were identified as possible sites of Zika virus outbreaks based on modeling studies1 and well-publicized outbreaks in Brazil and other areas of Latin America. Although there have been over 5,000 travel-related cases reported2 in the US since 2015, local transmission of the virus in the continental US occurred in just 224 cases in two geographic “pockets” last summer: Miami-Dade County, Florida (218 cases) and Brownsville, Texas (6). What does this summer hold for those of us on the lookout for Zika virus?

Zika: State of Play

Globally, the World Health Organization (WHO) reports Zika virus continues to spread to areas where mosquitoes are present that can transmit the virus. For example, the WHO recently reported three laboratory-confirmed cases of Zika virus in the Gujarat State of India. Because of the potential health effects on infants of infected mothers, the Centers for Disease Control and Prevention (CDC) tracks the number of pregnant women with any laboratory evidence of possible Zika virus infection in the US and US Territories (1,845 and 3,795, respectively, as of May 9, 2017). As of May 9, 2017, of 1,471 completed pregnancies reported to the US Zika Pregnancy Registry, there have been 64 liveborn infants with birth defects and 8 pregnancy losses with birth defects (approximately 5 percent birth defects).3

Currently, CDC data show nearly two-thirds of the 50 states have reported laboratory-confirmed cases of Zika virus in 2017. For the period January 1 – May 24, 2017, all 120 reported Zika virus cases were in travelers returning from affected areas. Many more cases, 498, were reported in US territories, with the majority in Puerto Rico. CDC presumes that all cases in US Territories were acquired through local mosquito-borne transmission. Meanwhile, Miami-Dade County and Brownsville are currently designated by CDC as “cautionary areas” to which pregnant women should consider postponing travel. In Florida, where I work at the Department of Health, none of the more than 90,000 mosquitoes tested to date have been found to be infected with the Zika virus, evidence that the virus has not “overwintered” here. We have a team of over 20 epidemiologists placed around the state to monitor Zika virus, and $20 million in state funds has gone to “skeeter control” districts for their spraying/larvaciding/eradication efforts. We are also aware that some cities and counties are planning to use genetically modified sterile mosquitoes to reduce mosquito populations.

Hope for a Vaccine

In a September 2016 interview, CDC director, Dr. Tom Frieden, noted that “Zika is likely to become endemic in this hemisphere. That means it will continue to spread at some level for years to come.” On the positive side, government scientists at the National Institute of Allergy and Infectious Diseases have developed an experimental vaccine that is being tested on human volunteers. According to the March 31, 2017 announcement, the trial is expected to conclude in 2019, but initial results could be available by the end of 2017. An effective vaccine will be critical in controlling the spread of Zika virus. Meanwhile, it’s important to implement the many known strategies that can help reduce our exposure to mosquitoes and Zika virus.

Tips from the Frontline of the Zika Virus Battle

The following tips include information from the Florida Department of Health’s “Drain and Cover” program, and can help control the risk of Zika virus and other mosquito borne illnesses:

  • Drain water from garbage cans, house gutters, pool covers, coolers, toys, flower pots, or any other containers where sprinkler or rain water has collected.
  • Discard old tires, drums, bottles, cans, pots and pans, broken appliances and other items that aren’t being used.
  • Empty and clean birdbaths and pets’ water bowls at least once or twice per week.
  • Protect boats and vehicles from rain with tarps that do not accumulate water.
  • Maintain appropriate pool chemistry (chlorine level and pH) of swimming pools. Empty plastic swimming pools when not in use and store in a way that avoids accumulating water.
  • Repair broken screens on windows, doors, porches and patios.
  • If you must be outside when Aedes mosquitoes are active (daytime), cover up. Wear shoes, socks, long pants and long sleeves.
  • Apply mosquito repellent to bare skin and clothing. Follow label directions. Repellents with DEET, picaridin, oil of lemon eucalyptus, para-menthane-diol, and IR3535 are effective and safe for pregnant and breast-feeding women, when used as directed. Use netting instead of repellents to protect children younger than two months.

Although it is difficult to predict how Zika virus will affect the US this summer, taking reasonable precautions to prevent exposure to mosquitoes is prudent, especially for those of us in vulnerable areas. Forewarned is forearmed!

Bob G. Vincent is an Environmental Administrator in the Florida Department of Health. He manages Department of Health programs for Healthy Marine Beaches, Safe Drinking Water, Water Well Surveillance and Public Pools and Bathing Places.


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1 These regions included the Gulf Coast and much of the Eastern Seaboard of the US.

2 Travel-related cases of Zika virus are those in which people are infected by mosquitoes while visiting countries in which the virus is endemic (regularly found). CDC reported 61 of these in 2015, 4,830 in 2016 and 119 as of May 19, in 2017.

3 CDC notes: “Although these outcomes occurred in pregnancies with laboratory evidence of possible Zika virus infection, we do not know whether they were caused by Zika virus infection or other factors.”


Avoiding Crypto at the Pool this Summer

Friday, May 26th, 2017
Sign on a door to a hotel pool in Santa Barbara, California, April 2017

Sign on a door to a hotel pool in Santa Barbara, California, April 2017

This summer the Centers for Disease Control and Prevention (CDC) and health departments across the country will strive to keep an unwanted parasite out of America’s pools, hot tubs and water parks. The microscopic organism, “Crypto,” short for Cryptosporidium, causes diarrhea and spreads through recreational water via the fecal-to-oral route. Yes, that’s a revolting image, but an awareness of how Crypto spreads can go a long way toward preventing outbreaks that can put a serious dent in your summer fun.

Crypto is not present in every pool, but according to CDC data, the number of US Crypto outbreaks in aquatic venues doubled between 2014 and 2016.

A Challenge for Chlorine

kidpoolAlthough chlorine destroys most disease-causing germs in treated recreational waters within minutes, Crypto presents a unique challenge. The issue is that in its infectious life stage, the parasite is protected from chemical disinfectants by a hard outer shell, known as an “oocyst.” Thanks to that resistant shell, Crypto can survive for days in a properly chlorinated pool.1

Destroying Crypto oocysts with chlorine requires hyperchlorination (also known as superchlorination)—a process in which the chlorine level of water is raised for a sufficient period of time (hours) during which the aquatic facility is closed to patrons. Hyperchlorination procedures can be found in the CDC’s Fecal Incident Response Guide, “What do you do when you find poop in the water?”. Some pool owners choose to hyperchlorinate weekly as a preventive measure. Oocysts also may be controlled by optimizing pool water filtration or by adding secondary treatment in the form of ultraviolet radiation or ozonation.

Four Ways to Outsmart Crypto

  1. Don’t Enter the Water if You Are Sick with Diarrhea: To avoid contaminating aquatic facilities with Crypto, CDC recommends not swimming when you are experiencing diarrhea or for at least two weeks after diarrhea ends, especially if you have been diagnosed with Crypto. Based on our recent Water Quality and Health Council survey, which found that 25 percent of respondents would swim within one hour of having diarrhea, this recommendation needs to “go viral.”
  1. Shower First: Showering is needed to remove swimmer perspiration, oils and cosmetics that deplete chlorine and form irritating byproducts. With regard to Crypto and other illnesses spread via the fecal-to-oral route, however, a soap shower is needed to remove the trace fecal matter (about 0.14 g) on each person’s bottom. Children under the age of five, who have poor hygiene, really need this, but do parents realize it? Our survey found that about half of adult swimmers don’t even rinse themselves off in the shower before swimming.
  1. Avoid Swallowing the Water: This could be difficult, but minimizing the amount of water swallowed helps reduce the risk of ingesting Crypto, developing diarrhea, and further spreading the parasite. Let children know that as cool and sparkling as it may look, pool water, like bath water, is not for drinking. Approximately 60 percent of adults who responded to our survey admitted they swallow water while swimming.
  1. Check and Change Swim Diapers: Swim diapers may not provide the perfect seal around a child’s bottom, but a well-fitted diaper kept securely in place is a helpful hygiene measure. Parents and caregivers can check diapers every hour or so to be sure “full” diapers are not being immersed in the pool, effectively creating a “fecal tea bag.” Change diapers only in designated areas away from the pool. Thorough hand washing after using the bathroom or handling diapers is essential, no matter the venue.

Crypto is now the leading cause of reported recreational water outbreaks. It is our hope that by highlighting the stark facts about this nasty parasite, future outbreaks will be avoided. Summer is too short to miss out on the fun of enjoying recreational water facilities.


Chris Wiant, M.P.H, Ph.D., is president and CEO of the Caring for Colorado Foundation. He is also chair of the Water Quality & Health Council and a member of the National Drinking Water Advisory Council.

Ralph Morris, M.D., M.P.H., is a Physician and Preventive Medicine and Public Health official living in Bemidji, MN.


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1 A properly chlorinated pool is one in which a minimum of 1 mg/L “free” chlorine is maintained.


Survey: 1 in 4 Adults Would Swim with Diarrhea

Tuesday, May 16th, 2017

Diarrheal outbreaks linked to swimming are a persistent challenge for aquatic venues

WASHINGTON, D.C. — Americans will soon head to the pool as Memorial Day weekend marks the unofficial start of the swimming season, but a new survey reveals that there may be more in the pool than just water.

The survey, conducted on behalf of the Water Quality and Health Council, found that 1 in 4 adults (25 percent) would swim within one hour of having diarrhea, half of adults (52 percent) seldom or never shower before swimming in a pool, and that 3 in 5 adults (60 percent) admit to swallowing pool water while swimming.

These results are concerning to experts from the U.S. Centers for Disease Control and Prevention (CDC), the Water Quality and Health Council, and the National Swimming Pool Foundation® (NSPF®), given that waterborne outbreaks of diarrheal disease caused by the germ Cryptosporidium (or “Crypto”) remain a challenging health concern.

Crypto is a parasite that can spread when someone swallows water that has been contaminated with the fecal matter (poop) of an infected swimmer. Crypto is the most common cause of diarrheal illness and outbreaks linked to swimming pools or water playgrounds. In addition to diarrhea, some people experience lack of appetite, nausea, vomiting, weight loss, stomach cramps or pain, and fever.

The CDC advises those infected with Crypto to avoid swimming until two weeks after recovering from diarrhea. Parasites can remain in the small intestine for weeks and cause symptoms to reappear days after the infected person recovers.

“Normal chlorine disinfection of swimming pool water does a great job in destroying most germs, but Crypto presents a special challenge,” said Dr. Chris Wiant, chair of the Water Quality and Health Council. “An awareness of Crypto helps us remember that a healthy pool depends on swimmers being considerate of one another. Showering before swimming, refraining from peeing in the pool, and not swimming for two weeks after experiencing diarrhea can help keep swimming fun and healthy for everyone from ‘water babies’ to seniors.”

Other key findings of the national Healthy Pools survey include:

  • 72 percent of adults are unaware that Crypto is a parasite often spread in water.
  • 84 percent of adults are unaware that the use of chlorine at CDC-recommended levels will NOT kill Crypto instantly in swimming pools.

Crypto is not easily killed by chlorine and can live up to 10 days in well-treated pools,” said Michele Hlavsa, RN, MPH, epidemiologist and chief of the CDC’s Healthy Swimming program. “Just a small number of Crypto germs can make someone sick. That’s why it is important to keep Crypto out of the water in the first place.”

Swimmers and parents of young swimmers can take a few easy steps to prevent Crypto outbreaks:

  • Stay out of recreational water (e.g., pools, lakes, rivers, oceans) if sick with diarrhea and until diarrhea-free for two weeks. Patients typically continue to shed Crypto for up to two weeks after diarrhea stops.
  • Shower before you get in the water. Rinsing off in the shower for just one minute removes most of the dirt or anything else on your body.
  • Don’t swallow the water.
  • Report diarrhea incidents that occur in the water to aquatics staff immediately.

Drowning prevention is also key to maintaining a healthy and safe swimming experience. According to the survey, 60 percent of parents reported engaging in some type of distracted activity while their children swam in a pool, such as using a phone or tablet, reading a book, drinking alcohol, sleeping or leaving the pool altogether.

“Parents should designate a ‘Water Watcher,’ because supervision can save a life,” said Thomas Lachocki, Ph.D., CEO of NSPF®. “Water Watchers are important even if a lifeguard is present. Water Watchers should be at least 16 years old and able to recognize and execute a rescue, provide a floating or reaching object, alert someone nearby to help or call 9-1-1, and be able to administer CPR.”

The Water Quality and Health Council is once again making free pool test kits available this summer through its award-winning Healthy Pools awareness initiative. Swimmers can test their backyard pools or community pools to ensure a proper pH and chlorine level. Visit to order a free pool test kit.

The 2017 Healthy Pools survey was conducted online by Sachs Media Group, an independent research firm based in Tallahassee, Fla. Sachs Media Group interviewed 3,114 adults (18+ years old), April 28-30, 2017. The survey measured perceptions and misconceptions related to swimming pools and public health, with a margin of error of +/- 2.0 percent.

To learn more about the Water Quality and Health Council and its efforts to raise awareness of the importance of disinfection for public health, please visit

Out of the Jungle: Yellow Fever on the Rise

Friday, May 5th, 2017
Brown Howler Monkey According to a recent Science Daily report, thousands of brown howler monkeys in a forest in southeastern Brazil have died of yellow fever.

Brown Howler Monkey

According to a recent Science Daily report, thousands of brown howler monkeys in a forest in southeastern Brazil have died of yellow fever.

Yellow fever, a deadly scourge transmitted by mosquitoes that has impacted the course of human history time and time again, is on the rise in Latin America. The first yellow fever death in Brazil in 17 years occurred in January 2017, when a young person who worked in the jungle succumbed to the disease. A recent Pan American Health Organization (PAHO) “Situation summary in the Americas” reported that since the current outbreak began in Brazil in December 2016, there have been over 1,400 confirmed or suspected cases and at least 234 deaths in six states of that country. Suspected and confirmed yellow fever cases have also been reported in Colombia, Ecuador, Peru, Bolivia and Suriname.

Yellow fever is indigenous to some tropical regions of Central and South America and Africa, and is caused by the yellow fever virus, one of a family of Flaviviruses, which includes West Nile virus, dengue virus and Zika virus. “Flavus” is Latin for “yellow.” Because it is borne by an arthropod (mosquitoes are arthropods), it is also known as an “arbovirus.” Yellow fever is the most severe arbovirus ever to circulate in the Americas, according to a recent commentary in The New England Journal of Medicine (NEJM).

Out of the Jungle

The yellow fever virus is transmitted through both a sylvatic (jungle) cycle and an urban cycle. According to the PAHO “Control of Yellow Fever Field Guide,” in the sylvatic cycle, the virus circulates among primates, primarily monkeys, through the bites of several species of mosquitos, and may result in death (see photo above). In the Americas, in the urban cycle, the virus is circulated among humans through the bite of the Aedes aegypti mosquito, the same mosquito that transmits Zika virus, chikungunya and dengue fever.

The urban cycle is initiated when a person who was infected with the disease in the jungle enters an urban center in which there is a high density of A. aegypti mosquitoes. If that individual is bitten by the A. aegypti mosquito while the virus is circulating in his or her blood, the disease can be spread to others subsequently bitten by the same mosquito, setting off a chain of transmission. Large outbreaks can result in urban areas where there are high mosquito densities and a high percentage of unvaccinated or otherwise unimmunized people. So far there is no evidence of urban transmission in Brazil.

Yellow Fever Symptoms

Following infection, the virus incubates in the human body for three to six days. Although many people develop no symptoms at all, fever, headache, jaundice, muscle pain, nausea, vomiting and fatigue may develop. Yellow fever is named for the jaundice exhibited by some patients. According to the World Health Organization, a small fraction of people infected with yellow fever develop severe symptoms and of those, approximately half die within seven to ten days.

A Vaccine and Vector Control

Fortunately, a very effective vaccine for yellow fever was developed in 1937 that is in wide use where the disease is endemic. According to the NEJM commentary, the current outbreak in Brazil is precariously centered in areas close to urban centers. Because urban Brazilians are not typically vaccinated against yellow fever, there is a concern that widespread urban transmission could begin, which could lead to “travel” cases in the US, such as we have seen with dengue, chikungunya and Zika viruses. Local US transmission can become a potential issue in regions such as the Gulf Coast states where A. aegypti mosquitoes thrive. In the age of world travel, we are a connected community, and with increasing tourism into jungle areas, the risk of importing yellow fever grows more likely.

As we know from recent experience with Zika virus, controlling the mosquito vector is a significant strategy for avoiding arboviruses. This includes removing outdoor standing water, properly chlorinating backyard swimming pools, maintaining window and door screens, and applying mosquito repellent appropriately (see tips). These are solid precautionary measures we can all take to help avoid any of the potential arboviruses circulating in our midst. Travelers to yellow fever endemic areas should ensure that they are immunized for yellow fever. Recently CDC announced a shortage of yellow fever vaccine, but noted there is a plan for providing safe vaccine at a limited number of clinics until the supply is replenished. For updates on the vaccine’s availability, please consult the CDC Travelers’ Health website. Travelers to areas in which yellow fever is endemic can also consider using bed netting, wearing protective clothing and applying mosquito repellent.

The more things change, the more they stay the same. Yellow fever is back (it never really went away), but unlike the devastating outbreaks documented throughout history, we now have proven effective measures to preclude them … if they are utilized.

Fred M. Reiff, P.E., is a retired official from both the U.S. Public Health Service and the Pan American Health Organization, and lives in the Reno, Nevada area.


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Color-coded Tips for Treating Algae in the Swimming Pool

Friday, April 28th, 2017

Algae Swimming PoolAlgae in the swimming pool is an unwelcome sight, but one that usually can be dealt with effectively. The following “color-coded” tips can help you or your pool service professional identify and eliminate, or at least control, the most common types of algae. It is important to follow manufacturers’ directions for using and storing all pool chemicals.

Green Algae

Green algae usually appears when pool sanitizer levels are low or water circulation is poor; green algae turns pool water cloudy and murky. It is the easiest type of algae to remediate, but left unaddressed, green algae can worsen to the point of obscuring the floor and steps of the pool and potentially even a struggling bather, raising the drowning risk. Eradicate green algae by raising the chlorine level or adding an algaecide. Following treatment, it is important to run the filtration system continuously to clear the water by trapping the dead algae in the filter.

Avoid green algae by maintaining proper pool chemical levels. Additionally, avoid cross-contaminating your pool with green algae spores by thoroughly washing swimsuits and water toys before re-using them in the pool following a visit to a natural water body.

Black Algae

Black algae appears as black dots on pool plaster, especially where the plaster is pitted, etched, or where calcium deposits have developed. Poor water circulation in those areas helps protect black algae. In fact, the more deteriorated the plaster, the worse the potential problem.

Tackle black algae as soon as it appears by scrubbing the affected area with a stainless steel brush. The scrubbing action removes a protective coating that develops over black algae. Daily brushing is required until the algae spots disappear. In severe cases, it may only be possible to control black algae, and not to eliminate it completely. It is essential to keep scrubbing black algae spots as soon as they appear.

An additional recommended step is to treat affected surfaces with “trichlor” on horizontal pool surfaces and a copper-based broad spectrum algaecide on vertical pool surfaces. Broad spectrum chelated copper algaecide can also be used as a preventative measure. A word to the wise: Have your pool water analyzed for metal levels prior to adding any metallic algaecide, such as copper-based products. If metals are present in the pool water, adding a metallic algaecide could cause the pool water to become oversaturated with metals, which could lead to staining or water discoloration. It is also advisable to keep copper to a minimum from a human toxicity standpoint. Most drinking water municipalities keep copper levels below 1.3 ppm. The manufacturers of copper algaecides should be able to provide the “ppm added” from use of their product. Excess copper in swimming pools can cause blue-green coloration of the hair, nails and skin.1

Yellow/Mustard Algae

Yellow or mustard-colored algae is probably the most challenging type of algae to eradicate. First, the diagnosis may be difficult. Yellow algae in a blue pool may look green, but the pool is not likely to contain green algae unless the water is cloudy and murky. Yellow algae may also be mistaken for dirt or pollen. The diagnostic test is to see whether or not the yellow substance returns to the side walls of the pool after it is scrubbed. Dirt or pollen will drop to the floor of the pool, but yellow algae will reappear on the walls.

To further complicate matters, yellow algae can thrive in a well-balanced chemically treated pool. It can be introduced into your pool from lakes, ponds, on the wind or in the rain. It can also be transmitted through previously contaminated pool equipment, such as skimmers, leaf rakes or vacuum hoses and heads. Treat yellow algae with an algaecide or chlorine enhancer that specifically targets yellow algae.

Anti-algae Basics

To help avoid algae of all types, keep in mind the basics of chemical and physical pool maintenance.

CHEMICAL MAINTENANCE: Proper pool chemistry means free chlorine and pH are within target ranges. According to the US Centers for Disease Control and Prevention’s Model Aquatic Health Code, pool water free chlorine levels should be in the range of 1-4 ppm and the pH should be between 7.2 (minimum) and 7.8 (maximum). The ideal pH in a pool is 7.4 to 7.6.

PHYSICAL MAINTENANCE: Physical maintenance of the pool means keeping up with brushing and vacuuming the pool and cleaning skimmer and pump baskets. Algae love rough and deteriorating pool surfaces, so sanding and crack repair are helpful. Clean pool filters as the first step in battling algae. Operating pumps and filters for at least 8 to 10 hours per day throughout the summer keeps water moving, a deterrent to algal growth.

This article is based on “Tips and tricks for identifying and treating tough algae,” by Terry Arko in the March 2017 edition of The IPPSAN, a publication of the Independent Pool & Spa Service Association, Inc.

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1 Peterson, J. et al. (2006). Cupric keratosis: green seborrheic keratoses secondary to external copper exposure. Europe PMC 77(1): 39-41. Abstract online, available:

Sweet Evidence for an Unsavory Practice: Peeing in the Pool

Friday, March 17th, 2017

PeeInPoolPeople urinate in swimming pools. It’s been a widely discussed topic since we published the results of our 2009 survey concluding that one in five American adults admit to having “peed in the pool.” Now there is physical evidence for this unsavory act, and it appears in the form of an artificial sweetener, of all things. A Canadian research team has identified a chemical compound in pool water that indicates the presence of urine. The “chemical marker” is acesulfame-K, or “ACE,” a synthetic sweetener found in prepackaged foods. ACE passes through the body essentially unaltered, and is excreted exclusively in the urine. The researchers posit that ACE could be a useful indicator of pool water quality.

The Problem with Peeing in the Pool

Besides being a rather discourteous thing to do, peeing in the pool contributes to poor pool water quality. Urine contains nitrogen-containing compounds that combine chemically with chlorine disinfectant to produce eye, skin and respiratory irritants. That strong chemical smell around some pools is not “the smell of chlorine,” but chemical products of chlorine’s reaction with urine, perspiration, cosmetics and body oils from swimmers. Chlorine, added to destroy waterborne pathogens that could make swimmers sick, is depleted by its reaction with these impurities. That’s why the Centers for Disease Control and Prevention encourages swimmers to shower before swimming and refrain from sneakily relieving themselves underwater.

Strategies to Avoid Using the Pool as a Toilet

We believe the key to ending peeing in the pool is multi-pronged and includes effective swimmer education and scheduled pool breaks, especially for young swimmers. We recommend swimmer hygiene messaging be a part of all swimming lessons and that clear signage around the pool encourage sanitary practices. Certain pool regimens also can be helpful. As the National Swimming Pool Foundation (NSPF) notes in a recent press release, being submerged in water stimulates the body to create more urine. NSPF offers the following commonsense recommendations to help prevent peeing in the pool:

  • Swim coaches should require bathroom breaks 30-60 minutes into practice.
  • Parents of young children should enforce a snack, sunscreen or bathroom “out of pool” time every 30 minutes.
  • Facility managers should schedule short breaks, such as 10 minute “adult swims” or out of pool activities every hour.

Swimming is fun and the health benefits of aquatic recreation are enormous. As evidence mounts that swimmers are fouling the very waters they enter to enjoy, the time is right to confront the problem.

Chris Wiant, M.P.H, Ph.D., is president and CEO of the Caring for Colorado Foundation. He is also chair of the Water Quality & Health Council and a member of the National Drinking Water Advisory Council.

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Smells Like Chlorine?

Friday, January 20th, 2017
Smells Like Chlorine

The nose is an extremely sensitive “detector” that sends information to the brain where it is interpreted.

They say “the nose knows,” but I say the nose can be confused. Chlorine odors are a good example. Several different chlorine odors can arise from various chlorine-based substances and in different circumstances. They are not all simply due to “chlorine.” A prime example is the irritating smell commonly attributed to chlorine around some poorly managed swimming pools. That smell is from a couple of chemical compounds in the chloramine family. Some chloramines form when chlorine disinfectants react chemically with nitrogen-based substances from the bodies of swimmers, including urine. The poolside pronouncement of “too much chlorine in the pool” may be more aptly described as “too much peeing in the pool.” Ironically, the odor could signal that more chlorine is needed in the pool.

Not One Chloramine

Chloramines start out as ammonia— NH3— which looks like a three-legged stool with the nitrogen atom as the “seat” and a hydrogen atom at the end of each “leg.” Ammonia is common in the environment, and Ammoniaalthough household ammonia has a very sharp odor, ammonia has no odor at the very dilute levels typically found in water. When chlorine is added to water in sufficient amounts, it breaks ammonia down into nitrogen (N2) gas and hydrogen (as water or H2O). But if the amount of nitrogen increases (from peeing in the pool, for example), the balance between chorine and nitrogen is disturbed and the ammonia is only partially deconstructed.

TrichloramineWhen three chlorine atoms replace the hydrogen atoms on the ammonia molecule, the resulting compound is trichloramine, a pungent, irritating compound that is often mistaken for “too much chlorine” in the pool, even at very low concentrations. Trichloramine and its sister chemical dichloramine (with two chlorine atoms and one hydrogen forming the “legs”) are responsible for the odor you might smell when you enter an enclosed pool area in which there is poor airflow through the building. Besides just smelling bad, these same two chemicals can also turn swimmers’ eyes red.

DichloramineThe problem with trichloramine and dichloramine goes beyond that irritating smell. When trichloramine is present in the pool, the level of “free chlorine” available to disinfect the water and protect swimmers from microbial disease is greatly diminished. That’s why it’s important to check pool water regularly for the pH and the presence of free chlorine1. Pool managers are obliged to do just that, and pool patrons can do the same with easy-to-use pool test strips.

MonochloramineTrichloramine and dichloramine have a third sister – monochloramine. As the name suggests, in this compound, only one of the hydrogen atoms on the ammonia has been replaced with chlorine. This chemical, however, carries no odor and is an effective disinfectant that has been used successfully by many water treatment plants for many decades. What a difference a minor change in a chemical formula can make!

Monochloramine is typically formed in source water by first adding chlorine to break down any ammonia (into nitrogen and water) and then adding back trace amounts of ammonia in carefully monitored amounts to produce only monochloramine.

Bleach Smell

Unlike the chloramine family of compounds, chlorine bleach is a solution of water and sodium hypochlorite with the chemical formula NaOCl [bleach contains sodium (Na), oxygen (O) and chlorine (Cl)]. The odor of bleach (bleach that is not infused with a fragrance) is not nearly as pungent as that of di- and trichloramines. When the chlorine in bleach combines with nitrogen-based substances, however, smelly di- and trichloramines can form by chemical reaction. This could happen in the swimming pool environment, for example.

Chlorine Gas

Chlorine is a common, naturally occurring element, but due to its reactivity, it usually occurs in nature combined with other elements, such as sodium in common table salt, NaCl. It is also produced industrially as part of the “chlor-alkali” process in which both chlorine and sodium hydroxide (NaOH) are generated by applying electricity to salty water. In that process, chlorine is produced as a gas consisting of twin atoms chemically bound together, and is represented by chemists as “Cl2.” Both chlorine and sodium hydroxide are used to help produce hundreds of everyday products, including water treatment chemicals, PVC pipes, pharmaceuticals, paper, aluminum, silicon chips for computers and even the titanium metal used in joint replacements.

Chlorine gas is a respiratory irritant that the human nose can detect at very low levels (0.2-0.4 parts per million in air; just for reference, one part per million is equivalent to four drops of ink in a 55-gallon barrel of water). At these low concentrations, chlorine gas smells very much like household bleach. When levels rise to the range of 1-3 ppm, however, mild mucous membrane irritation is noted and higher level exposure becomes increasingly dangerous.2 That is why the chlor-alkali industry takes extensive measures to ensure the safe production, handling and transportation of chlorine gas and even the less reactive sodium hypochlorite and calcium hypochlorite.

Not Just One Chlorine Compound

Chlorine is a reactive element that is found in many different compounds exhibiting different but sometimes similar properties, including odor. It is credited to have dramatically improved public health over the past 100 years through its ability to disinfect water.  I hope this discussion helps to clarify “the smell of chlorine.” Now your nose knows! 

Stephan A. Hubbs retired from water treatment operations at the Louisville Water Company in 2004. He was involved in the development of the first chlorine by-products regulation in 1975-1979 and remains an active volunteer in the drinking water community today.

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1 Hypochlorous acid, or HOCl, for you chemists!

2 The Chlorine Institute, Inc., Pamphlet 63: First Aid, Medical Management/Surveillance and Occupational Hygiene Monitoring Practices for Chlorine, Edition 8, June, 2011.