TTHM Violations

IMPORTANT INFORMATION ABOUT YOUR DRINKING WATER
Total Trihalomethanes (TTHM) MCL Violation at Nyack Water System
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 did (are doing) to correct this situation.

We routinely monitor for the presence of drinking water contaminants. Testing results from October 2025 through July 2026 show that our system exceeds the standard, or maximum contaminant level (MCL), for Total Trihalomethane (TTHM). The standard for TTHM is 80 ug/L. It is determined by averaging all the samples collected at each sampling location for the prior 12 months. The level of TTHM averaged at two of our system’s sample locations was 87 ug/L and the other was 82 ug/l.

What should I do?
•There is nothing you need to do. 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.
• If you have a severely compromised immune system, have an infant, are pregnant, or are elderly, you may be at increased risk and should seek advice from your health care providers about drinking this water.

What does this mean?
This is not an emergency. If it had been an emergency, you would have been notified within 24 hours.
Trihalomethanes 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 trihalomethanes 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. All public water systems that use chlorine as a disinfectant contain trihalomethanes to some degree.

The following paragraph summarizes and characterizes the available studies on human populations exposed to trihalomethanes, and provides a general summary of the health effects of trihalomethanes 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 water containing trihalomethanes for long periods of time (e.g., 20 to 30 years) have an increased risk of certain health effects. These include an increased risk for cancer and for low birth weights, miscarriages and birth defects. The methods used by these studies could not rule out the role of other factors that could have resulted in the observed increased risks. In addition, other similar studies do not show an increased risk for these health effects. Therefore, the evidence from these studies is not strong enough to conclude that the observed increased risk for health effects is due to trihalomethanes, other disinfection by-products, or some other factor. Studies of laboratory animals show that some trihalomethanes can cause cancer and adverse reproductive and developmental effects after high levels of exposure. The risks for adverse health effects from trihalomethanes in drinking water are small compared to the risks for illness from drinking inadequately disinfected water.

What is being done?
The Village of Nyack Water Department has installed the new GridBee TTHM (Total Trihalomethanes) removal system beginning on August 11th, 2026 and completed August 28th, 2026. In addition, installation of the Kupferle 9200 automatic hydrant flusher at Piermont Avenue and Smith St in South Nyack was approved on September 14th, 2026. Nyack Water continues to conduct semi-annual system hydrant flushing and increased end-of-system hydrant flushing to increase water movement throughout the entire system. For more information, please contact Thomas Lynch, Superintendent of Nyack Water, at 845-358-3734 or thomaslynch@nyack-ny.gov, or the Rockland County Department of Health at 845-364-2608.

*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 Village of Nyack Water Department.
State Water System ID#: 4303666
Date distributed: 9/17/26