An answer to the perennial question: Is it safe to pee in the pool?

An answer to the perennial question: Is it safe to pee in the pool?

Sanitary-minded pool-goers who preach "no peeing in the pool," despite ordinary and Olympic swimmers admitting to the practice, now have scientific evidence to back up their concern. Researchers are reporting that when mixed, urine and chlorine can form substances that can cause potential health problems. Their study appears in ACS' journal Environmental Science & Technology.

Jing Li, Ernest Blatchley, III, and colleagues note that adding to pool water is the most common way to kill disease-causing microbes and prevent swimmers from getting sick. But as people swim, splash, play—and pee—in the pool, chlorine mixes with sweat and urine and makes other . Two of these compounds, including trichloramine (NCl3) and cyanogen chloride (CNCl), are ubiquitous in swimming pools. The first one is associated with lung problems, and the second one can also affect the lungs, as well as the heart and central nervous system. But scientists have not yet identified all of the specific ingredients in sweat and urine that could cause these potentially harmful compounds to form. So Li's team looked at how chlorine interacts with uric acid, a component of sweat and urine.

They mixed uric acid and chlorine, and within an hour, both NCl3 and CNCl formed. Though some uric acid comes from sweat, the scientists calculated that more than 90 percent of the compound in pools comes from urine. They conclude that swimmers can improve pool conditions by simply urinating where they're supposed to—in the bathrooms.

Explore further

First measurements of HAAs in urine of swimmers and pool workers

More information: "Volatile Disinfection Byproducts Resulting from Chlorination of Uric Acid: Implications for Swimming Pools" Environ. Sci. Technol., 2014, 48 (6), pp 3210–3217. DOI: 10.1021/es405402r

Cyanogen chloride (CNCl) and trichloramine (NCl3) are important disinfection byproducts in chlorinated swimming pools. However, some unknowns exist regarding the precursors of their formation. In this study, uric acid is shown to be an efficient precursor to formation of CNCl and NCl3. The molar yields of CNCl and NCl3 were observed to be as high as 44% (pH = 6.0, chlorine/precursor molar ratio [Cl/P] = 6.4) and 108% (pH = 7.0, Cl/P = 30), respectively, both being strong functions of Cl/P, pH, and temperature. Analysis of swimming pool water samples, combined with the results of experiments involving chlorination of uric acid, and chlorination of body fluid analog mixtures, indicated that uric acid chlorination may account for a large fraction of CNCl formation in swimming pools. Moreover, given that uric acid introduction to pools is attributable to urination, a voluntary action for most swimmers, these findings indicate important benefits to pool water and air chemistry that could result from improved hygiene habits on the part of swimmers.

Citation: An answer to the perennial question: Is it safe to pee in the pool? (2014, March 26) retrieved 19 August 2019 from
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

Feedback to editors

User comments

Mar 26, 2014
Some years ago, around 10 AM on a Monday, I was the only swimmer in our local municipal pool. Happily doing lengths, I was very surprised when an attendant came along with a bucket, and tipped about five kilos of white crystals into the water.
WTF ??
'Sodium Carbonate -- Washing soda. We've a party of school-kids from {deprived district} arriving in half an hour. They WILL NOT shower, use the wade-pool or toilets before jumping in. This neutralises the nasties the Chlorine creates...'
Okay, fair enough, but my eyes already stung from the upper-limit Chlorine content. Thirty seconds later, I was hastily showering, before towelling myself dry and fleeing. At least I hadn't paid for a week...

Mar 27, 2014
I also remember what should have been a fun weekend in Midlands ruined by our smart hotel over-chlorinating their pool. Half an hour left us red-eyed and without appetite. I sent hotel a *stinker* of a letter listing our dismay and alternative treatments, heard nothing back. Several months later, the same hotel was on news for their midnight evacuation due to a Chlorine escape...

FWIW, next time we passed there, the pool was shut 'Until Further Notice'. Still, at dawn the following morning, a sous-chef managed to ignite the heavy fat spatter in an extract hood, so staff and guests had to evacuate into the inevitable rain...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more