The water delivered to about 350 homes in the development exceeds state limits for trihalomethanes, compounds believed to raise cancer risks.

The Department of Public Health has been concerned about the problem for four years. Changes to the system brought the water district into compliance for about nine months last year, but the trihalomethane levels have risen to unacceptable levels again during the past nine months, according to the Department of Health.

Trihalomethanes occur in drinking water systems as a result of the process of disinfecting the water. The Department of Public Health wants Western Hills Water District to install a filtration system to remove the chemicals that form trihalomethanes after the disinfection process.

The water district had proposed an aggressive flushing program using fire hydrants on the system to resolve the problem, but the Department of Health concluded that would be too expensive to sustain and would waste too much water.

The Department of Health citation carries a $1,000 fine and orders the water district to comply with water standards. It spells out a timeline for the water district to get into compliance. Plans for a different disinfectant system should be submitted to the state by Sept. 1, according to the order, and the water district should start using a new filtration system by July 31 as an interim measure. Failure to comply with the deadlines could result in a $1,000 fine per day.