Important Information About Your Drinking Water

Haloacetic Acid 5 (HAA5) MCL Violation at Westchester Joint Water Works

Our water system recently violated a drinking water standard. Although this incident was not an emergency, as our customers, you have a right to know what happened and what we are doing to correct this situation.

Quarterly water samples were taken for haloacetic acids on 7/23/2018, 10/22/2018, 1/22/2019 and 4/22/2019. The total haloacetic acid concentrations were 0.042, 0.071, 0.086, and 0.045 parts per million (ppm), and averaged 0.061 ppm for the last year at one location.  This average level is slightly above the state and federal drinking water standard of 0.060 ppm total haloacetic acids as a running annual average of four quarterly samples.

What should I do?

There is nothing you need to do unless you have a severely compromised immune system, have an infant, or are elderly. These people may be at increased risk and should seek advice about drinking water from their health care providers.

You do not need to boil your water or take other corrective actions. If a situation arises where the water is no longer safe to drink, you will be notified within 24 hours. We will announce any emergencies on News12 Westchester or other local news networks (CBS, NBC, ABC, and FOX).

What does this mean?

This is not an emergency. If it had been an emergency, you would have been notified within 24 hours.

Haloacetic acids are disinfection byproducts formed during treatment of drinking water by chlorine, the most commonly used disinfectant in New York State. Drinking water is disinfected by public water suppliers to kill bacteria and viruses that could cause serious illnesses. For this reason, disinfection of drinking water by chlorination is beneficial to public health. The amount of haloacetic acids in drinking water can change from day to day, depending on the temperature, the amount of organic material in the source water, the amount of chlorine added, and a variety of other factors.

The presence of haloacetic acids at the concentrations detected in the water system does not constitute an immediate health hazard. Although the standard is slightly exceeded, it is not a "bright line" between drinking water concentrations that cause health effects and those that do not. The standard for haloacetic acids is set at a water concentration at which exposure is much lower than exposures identified as causing health effects in animals. Thus, exceedance of the standard is not a trigger for health effects, but a trigger for water suppliers to take action to reduce the haloacetic acid concentrations and maintain what is already a large margin of protection against health effects. The risks for adverse health effects from the haloacetic acids in the drinking water are small compared to the risk for illness from drinking inadequately disinfected water.

This paragraph summarizes and characterizes the available studies on human populations exposed to haloacetic acids, and provides a general summary of the health effects of haloacetic acids in animals, which occur at exposure levels much higher than exposures that could result through normal use of the water. Some studies suggest that people who drank chlorinated drinking water containing disinfection by-products (including haloacetic acids) for long periods of time (e.g., 20 to 30 years) have an increased risk for cancer. However, how long and how frequently people actually drank the water, and how much haloacetic acids the water contained is not known for certain. Therefore, the evidence from these studies is not strong enough to conclude that the observed increased risk for cancer is due to haloacetic acids, other disinfection by- products, or some other factor. Studies of laboratory animals show that the two haloacetic acids, dichloroacetic acid and trichloroacetic acid, can cause cancer following exposure to high levels over their lifetimes. Dichloroacetic acid and trichloroacetic acid are also known to cause other effects in laboratory animals after high levels of exposure, primarily on the liver, kidney, and nervous system and on their ability to bear healthy offspring.

What happened? What is being done?

Haloacetic acids are formed by the exposure of natural organic materials to the chlorine used for disinfection. The amount of time this material is exposed to chlorine increases the formation of disinfection byproducts. An immediate mitigation we have implemented is reducing the amount of chlorine levels in the system to more efficiently treat the water for pathogens

We have obtained a consultant to study and review system operations to determine if system infrastructure modification or new treatment measures can be deployed to reduce the levels of disinfection byproducts in our water system. This study has been completed and Westchester Joint Water Works has implemented ways to reduce the HAA5 levels in the system.  We have minimized the overall chlorine dosage in the system which assists to prevent these formation of disinfection byproducts. We have implemented a more rigorous hydrant flushing program as well as dropped the elevation of our water storage tanks to reduce the age of water. Thus, shrinking the time period when these by-products can be created.

For more information, please contact Frank Arcara, Chief Water Treatment Plant Operator, at (914) 698-3500 or the Westchester County Department of Health at (914) 813-5000.

Please share this information with all the other people who drink this water, especially those who may not have received this notice directly (for example, people in apartments, nursing homes, schools, and businesses). You can do this by posting this notice in a public place or distributing copies by hand or mail.

This notice is being sent to you by the Westchester Joint Water Works.

State Water System ID#: 5903435