The number of confirmed cases of Cryptosporidium infections has increased to 16, Tarrant County Public Health said Tuesday.

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Pool manager Jesse Bradley pours chlorine into the pool at Bad Konigshofen Outdoor Family Aquatic Center at Stovall Park in Arlington on Wednesday.

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Meanwhile, the city of Arlington is following the request of the health department to hyperchlorinate all public swimming pools. All seven of the city's public pools will be closed today to allow for the treatment, which introduces large amounts of chlorine into the water. The pools are scheduled to reopen Thursday.

Health officials are still waiting for the results of tests that were done on water samples taken from the spring-fed Burger's Lake in West Fort Worth, which could be the source of the outbreak. The water samples were sent to the Centers for Disease Control and Prevention in Atlanta.

Earlier, the health department tested the water used to fill Burger's Lake for fecal contamination, which is how cryptosporidiosis is usually spread. Results came back negative.

The owner of the Burger's Lake closed the swimming hole last week while health officials investigated the outbreak of cryptosporidiosis. The disease can result in stomach cramps, diarrhea, vomiting and dehydration.

The health department has asked that all public pools – including those in Dallas, Collin and Denton counties – be hyperchlorinated to prevent further infections.

"No evidence of this parasite has been found in any city of Arlington pool, and we want to assure the public our water is safe," Bill Gilmore, assistant parks director in Arlington, said in a news release.