Goggles please! Swimming pools contain gallons of urine

THE average swimming pool includes gallons of urine, and the chlorine that is used to deactivate it is much less effective than previously thought, a new study has revealed.

The first major study of its kind has shown that swimmers in an Olympicsized pool could be surrounded by up to 50 gallons of urine.

Researchers discovered the sweetener acesulfame potassium, ACE, is consistently present in urine, “making it easy to monitor pool levels.”

Surveys suggest nearly one in five adults, including professional swimmers, admits urinating in a pool at least once, with the average urine excretion per swimmer of approximately 70ml.

Despite urine itself being relatively sterile, compounds can react with disinfectants such as chlorine, causing them to become volatile. Exposure can lead to eye and respiratory irritation and has been linked to occupational asthma.

The researchers tested more than 250 water samples from 31 actively used pools and hot tubs in two Canadian cities and more than 90 samples of clean tap water used to fill the pools.

The concentration of ACE in the pools and hot tubs ranged from 30 to 7,110 nanograms (about a 25,000,000th of an ounce) per litre of water, up to 570 times more than the levels found in the tap water samples.

Dr Xing-Fang Li, from the University of Alberta, said the new evidence highlighted the need for improved understanding of pool chemistry. “This is the first reported occurrence study of ACE in swimming pools and hot tubs,” he said. “The high concentration of ACE, with 100 per cent occurrence in pools and hot tubs, demonstrates the human impact on recreational water quality.

“The association of asthma in swimmers with volatile disinfection byproducts highlights the need to control the water quality of swimming pools.”

The findings were published in the journal Environmental Science and Technology Letters.