Chlorine Disinfection Byproducts in Tap Water & Reproductive Health

Over the past several years, a handful of studies have shown a possible link between high levels of chlorine disinfection byproducts in tap water and adverse effects on reproductive health, including low birth weight and miscarriage.

The first study, conducted in 1998 by the California Department of Health Services (DHS) studied women who reported consuming 5 or more glasses a day of tap water that contained at least 75 micrograms per liter of total trihalomethanes (TTHM), which are byproducts created when chlorine contacts the organic matter that is routinely present in untreated water and found a possible linkage to 1st trimester miscarriages.

At the time of the study (1998), the maximum contaminant level (MCL) for TTHM set by the state and federal governments was 100 micrograms per liter. Since, it has been lowered to 80 micrograms per liter.

There is a significant amount of debate within the scientific community over the accuracy of these studies. Other studies have failed to demonstrate a linkage between byproducts and miscarriage. Studies continue to be conducted to better define the situation.

What About CCWD's Water?
  • Water quality at the tap depends on both the quality of source water and the quality of water treatment. CCWD places a high priority on protecting its source water and providing state-of-the-art water treatment.
  • CCWD's treated drinking water is consistently below all state and federal drinking water standards. TTHM in CCWD treated water averages well below the level allowed by state and federal health regulations and the level cited in the 1998 California study that linked TTHM levels to miscarriage. In 2002, CCWD treated water had an average TTHM level of 36 micrograms per liter.
  • Over the past 10 years, CCWD has invested more than $100 million in the Ralph D. Bollman Treatment Plant in Concord and the Randall-Bold Water Treatment Plant in Oakley. Both of these plants are state-of-the-art and use ozone gas for primary disinfection.
  • Using ozone gas for primary disinfection at CCWD's state-of-the-art treatment plants keeps chlorinated disinfection byproducts low.
  • Chloramine (a combination of ammonia and chlorine) is used for residual disinfection after the treated water leaves the treatment plants. Using chloramines for this purpose also helps keep disinfection byproducts low.
If You Are Pregnant
Pregnant women with concerns should talk to their physicians about their health. For more information about their water quality and their drinking water system they can review CCWD's Annual Water Quality Report. Call 925-688-8109 or email CCWD to receive a printed copy of the Annual Water Quality Report for communities in the CCWD service area.

For more information call the CCWD Water Quality Hotline at 925-688-8156.