How Clean Are Public Swimming Pools?
Warm weather is in the forecast for today and on into the weekend. That may have you thinking about cooling off at one of Austin’s 50 public pools and splash pads. It’s June, so they’re all open for business. People bring a lot into the pools with them – sweat and a slurry of other bodily fluids – and the city is making an effort to keep them clean.
At Northwest Municipal Pool in the Allandale neighborhood, pool supervisor Daniel Otero dips two plastic test tubes into the water.
“You want to turn it upside-down so you’re not getting the surface water because the sun burns off the chemicals at the top,” he says. “You kind of want to go about a foot down under the water, flip it over and get that water sample.”
Otero pulls the tubes out of the water, drops some colored liquids in and compares the color to a chart on the test kit. He’s looking for a chlorine level of between one and five parts-per-million.
“We have a 1.5 [chlorine level],” Otero says. “And then for your [pH] levels you want between a 7 and a 7.8, so we’re perfect.”
This process is done every hour at all of the city’s chlorinated pools – twice as often as required by state law. Tom Nelson is the division manager in charge of city pools.
“We want to ensure that the pools are operating smoothly and efficiently,” Nelson says. “That’s the reason we check them once an hour, just to make sure that they’re property sanitized.”
One concern for these public pools is that you never know what other people could be bringing into the water with them. A recent poll by industry advisors from the Water Quality and Health Council found that seven of ten adults don’t shower before swimming. And one in five adults admitted to peeing in the pool, according to the poll. Microbiologist Joan Rose is a member of the Water Quality and Health Council.
“Often we hear, ‘Urine’s sterile, right?’ So we need to really educate people that urine is not sterile. It can be passing viruses,” Rose says. “In addition, it uses up the disinfection – the protection that we have in these swimming pools.”
When chlorine mixes with things like urine and sweat, it forms into something called chlorimines. That’s what creates that famous pool scent that you think is chlorine. Chloramines can cause your eyes to turn red when you swim, but at least then you know the chlorine is doing its job.
The real worry for public health officials is the stuff that chlorine can’t kill: pathogens lurking deep beneath the water. Michele Hlavsa runs the Healthy Swimming Program at the Centers for Disease Control and Prevention.
“The one we’re concerned about right now is crytosporidum, or cryto for short,” Hlavsa says. “Studies have shown that if you swallow 10, you can become infected and have diarrhea for two to three weeks. I have reports of patients having 40 bowel movements a day.”
She says it’s still kind of rare, but is becoming more common. A 2007 outbreak in Utah affected more than 5,000 people. And closer to home, more than 2,000 people in East Texas were affected by an outbreak in 2008. (You can read the CDC’s latest outbreak report here.)
The most effective way to kill cryptosporidium is with ultraviolet light and ozone filters, Hlavsa says. But installing those would cost an estimated $30,000 per pool.
“At this time, many pool operators are finding the price inhibitory,” Hlavsa says. “But then again, I think pool operators also need to weigh that against the possibility of having an outbreak and a lawsuit.”
The city of Austin does have ultraviolet light filters on its 10 splash pads, like the one at Butler Park. But UV or ozone filters are not used in its swimming pools.
Bottom line: follow the advice of public health experts like Rob Emery at the University of Texas School of Public Health.
“The most basic thing that one can do is don’t get the water in your mouth,” Emery says. “Be an observant swimmer and look at the conditions in the pool, and take control of the things that you have control over – good swimmer hygiene and keeping the water out of your mouth.”
The city’s most popular swimming spot – the Barton Springs Pool – is not chlorinated because it’s fed by an underground spring. The city tests it regularly for E. Coli bacteria.