Johnson Utilities reports there are higher-than-normal levels of nitrates in the water for about 10,000 San Tan Valley customers.

“We discovered it was from a particular well and we removed that well from services,” said Brad Cole, chief operating officer for Hunt Management, which is responsible for Johnson Utilities.

Infants less than 6 months old and pregnant women should not drink the water until Friday.

Nitrate is a naturally occurring nutrient, but when levels are too high, it can prevent blood from carrying oxygen. Newborns and pregnant women are most vulnerable to health problems.

Cole advises customers in Johnson Ranch, Copper Basin, Rancho Bella Vista and Rancho Bella Vista South subdivisions to be cautious.

“First and foremost, do not boil the water. That concentrates the concentration of nitrates,” Cole said.

The utility plans to connect new wells to the system to prevent contamination in the future.