New Technology Tests Water Safety

Fifteen years ago, if you went out to Reef Bay on St. John on a weekend, you’d see a half-dozen, very determined pre-teen girls on surfboards learning to find their balance and ride the waves. Most of them still claim a passion for water sports, and one of them, Katie Day, has gone on to become an activist for clean water.

Day now works for the Surfrider Foundation, a non-profit organization based in San Clemente, California. She was back on St. John for several weeks in October bringing innovative technology to field test for harmful bacteria in water.

“We’re going around to the more popular swimming beaches and testing for E. Coli, which is a ‘fecal indicator’ bacteria,” Day said. “When you see E. Coli, it’s an indication of other pathogens, including staph, which can cause stomach problems and skin rashes.” People with compromised immune systems or open wounds are particularly vulnerable to these infections, she said.

Mud plumes from runoff in Rendezvous Bay on Saturday, Oct. 28.

The Department of Planning and Natural Resources regularly tests the water at popular swimming beaches throughout the territory for a different type of bacteria, Enterococci, and for water clarity. The National Park Service does the same for beaches within its jurisdiction. But the time between testing and the publication of results often takes the better part of a week, and conditions often change because of stormwater runoff, sewer system overflows, and dynamic surf conditions.

“Normally you have to do this testing in a laboratory, culturing the bacteria and allowing it to incubate. We’re using test kits made by Aquagenx. Their technology allows us to get results in the field without electricity, usually within two days.” The Surfrider Foundation and Love City Strong independently tested beach water quality at 14 beaches over a seven-day period.

Day said results published by DPNR on October 27 for tests conducted between October 23-27 indicated that Cruz Bay was safe for swimming. However, results from the Aquagenx test on October 26 for Cruz Bay indicated a high risk of pathogens.

STJ Beach Water Results_Oct30

Day was quick to explain that rain earlier that day could have led to the difference in results. Conditions are dynamic, she explained. “This is why we always list the most recent date of prior rain next to our results.” Day said that samples taken at two different locations at the same beach may show different results.

For example, a water sample taken at Maho Bay on October 17 near the site of the old pavilion indicated a Most Probable Number (MPN) of bacteria at 136 per 100 ml., showing a medium risk of E. Coli infection. But a sample taken at the same time from the opposite end of the beach where a ghut empties out showed an MPN of 326, indicating a high risk.

Katie Day (left) and Sarah Swan (right).

E. Coli bacteria are present in the feces of humans, animals and birds, said Day, so the presence of a large flock of sea birds could affect test results.

The Aquagenx system, which included 100 test kits, was donated by the Surfrider Foundation. Efforts to make the tests available over the next several months are continuing. Love City Strong, a community organization, has donated funds to bring more tests to the island and is publishing results of beach tests on their Facebook page. Results are also being posted at VI National Park headquarters, Connections, and the Coral Bay fire station.

The tests work equally well for cistern water. Several St. John residents were surprised to discover the tests showed contamination of their cisterns in their homes.

Sarah Swan, who surfed with Katie as a girl and has returned to live on the island, has been trained to conduct the tests and follow up on results.

Katie shows Tammy Cummings how to use water filter.

Individuals who would like to have their cisterns tested can contact them at or They’re requesting a $20 donation from those who can afford it to defray the cost of the tests, according to Day. Donations for the water testing program can also be made to the Surfrider Foundation or Love City Strong.

Day, who has a Masters of Environmental Science and Management from UC Santa Barbara, also had a solution for those whose drinking water isn’t safe. On Monday she was handing out free water filtration systems donated by Waves for Water, an NGO that works to bring clean drinking water to underserved populations throughout the world. St. John Hardware donated the buckets used to collect the filtered water.

Day distributed 60 water filtration systems during her visit and is working with community organizations to make more of them available.