Due to a number of telephone inquiries regarding a recent tap water study in California, both the Water Authority of Western Nassau County and the Nassau County Department of Health advises residents that the public water supply in Nassau County is consistently monitored for quality. It meets all federal, state and local drinking water standards and is safe to drink.

A recent study in California examined exposure to trihalomethanes and its relationship to miscarriages within the first 20 weeks of pregnancy. That study found a modest association between drinking tap water containing trihalomethanes and miscarriages. The risk of miscarriage increased for women who drank five or more glasses of water daily when the trihalomethanes levels were greater than 75 micrograms per liter. Miscarriages can be caused by many factors including smoking, older maternal age and previously having had a miscarriage.

According to the water supplier, in New Hyde Park, Water Authority of Western Nassau County Chief Engineer Robert Swartz, "The water supplied by the Water Authority of Western Nassau County (the Water Authority) is routinely monitored for quality and is safe to drink. Of recent concern is the level of trihalomethane in the water. The total trihalomethane potential (TTMP) of six samples taken from the Water Authority's distribution system during 1997 range between 6 and 18 ug/1 (parts per billion parts) with an average of 10.5 ug/l. In 1996 TTMP ranged between 12 and 26 ug/l with an average of 22.2 ug/l. The actual total trihalomethanes (TTHM) for 1996 ranged between < 0.5 and 6.3 ug/l with an average of 0.8 ug/l. The TTHM for 1997 will be available in April of 1998. Federal and state drinking water standards limit trihalomethanes to an annual average of 100 ug/l. The Water Authority's results are well below the limit."

Chlorinating drinking water is necessary to prevent potential diseases such as gastrointestinal illnesses caused by bacteria, viruses and other microorganisms. When chlorine is added to water with organic matter (leaves, etc.) trihalomethanes are formed. Because of higher organic matter content, drinking water taken from surface water (streams, lakes, reservoirs) generally have higher trihalomethane levels than drinking water obtained from wells.

Swartz added, "The Water Authority tests for approximately 145 different constituents in the water including trihalomethanes. Samples are taken from 100 distribution system locations on a monthly basis and its wells are sampled continuously throughout the year. The Water Authority meets all current standards for drinking water. In addition to sampling, Water Authority personnel monitor each well that is operating on a daily basis to assure that the proper amount of treatment is being added to the water."

In Nassau County, all public water suppliers use wells to draw ground water from aquifers found under Long Island. They do not draw water from surface supplies. These waters in Nassau County have lower organic matter content and, therefore, use of chlorination does not result in trihalomethanes at levels associated with the health risk found in the California Study.

For those residents who wish to consider reducing trihalomethane exposure, the New York State Department of Health recommends:

* Boil tap water for several minutes and cool before drinking.

* Pregnant women and anyone should be sure to drink 6-8 glasses of water a day unless their doctors advise otherwise.

* Contact the Water Authority of Western Nassau County if you want the most recent trihalomethane water quality results at 327-4000.