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TTHM Information

What are TTHMs?
Trihalomethanes (also known as THMs, TTHMs, or DBPs (disinfection by-products)) refer to a group of chemical compounds that form when chlorine reacts with organic matter present in water. Organic matter is present in water at varying levels, with higher content found in surface water. Increased temperature and water age encourage formation of TTHMs.

The Environmental Protection Agency (EPA) has recently changed the limit of allowable TTHMs in drinking water to 80 parts per billion (ppb). This total refers to an annual running average; meaning that the TTHM readings over the course of a year must average less than 80ppb. The Town of Ulysses levels in Water District 3 have been over that limit several times in the last few years. The EPA states that "Some people who drink water containing total trihalomethanes in excess of the MCL over many years could experience liver, kidney, or central nervous system problems and increased risk of cancer."


The Town Board of the Town of Ulysses has been working on a remediation plan with 2 engineering firms: Hunt and the MRB Group.

Letter to TTHM group from Supervisor Thomas 3-23-16

Correspondence from MRB Group 5/8/15

Town Board Resolution 2014-200- Authorizing an Aerator

Conclusion from Hunt Engineer report 10/3/14

Citizen Involvement

The Town appointed five Water District 3 users to the "TTHM Working Group" to be involved in the remediation process and share information with other users in the district. Meetings are held on as-needed basis.
Ann DiPetta
Diane Hillmann
Stan Seltzer


TTHM testing

TTHM Annual Running Average

For more information on water quality testing in Water District 3, click here.

Other Information

Update from Supervisor Thomas 5/29/15

Ulysses Progress Report to Dept. of Health 5/12/15

Letter from Dept. of Health to Ulysses 12/24/14

Ulysses Progress Report to Dept. of Health 11/14


What can Water District 3 users do about TTHMs until the problem is fixed?

According to the EPA, use of a carbon filter (such as a Brita) will significantly reduce TTHMs if the filter is properly maintained.