Trade-offs

Residents of Lisbon, NH have to boil their water until further notice. Coliform bacteria, indicators of possible contamination, showed up in the town's wells after heavy rains. The bacteria made it into the water system because chlorination had been shut down.

According to Terry Welch, owner of Welch’s Water Services in Lisbon, the bacteria count in the tested sample was minimal. “Chlorine would have killed the [bacteria] right away,” he said. The town’s water facilities have been maintained and operated by Welch’s Water Services for eight years. Before Welch’s took over operations, Lisbon’s water was not chlorinated. When they came on board, they immediately began chlorination. Welch’s Water Services also operates the municipal wastewater treatment plant. They were so successful in turning the run-down facility into a well-operated and maintained plant, that in 2003, the plant was selected by the U.S. Environmental Protection Agency for the national Operations and Maintenance Excellence Award. Last January, the EPA suggested that Welch turn off the chlorinators for the town’s water supply. They informed him of the health risks associated with chlorine, and the potential environmental impacts from chlorinated water entering surrounding lands. At the time, Lisbon was one of the few towns in New Hampshire to draw its water from a well and still employ chlorination. Concerned about the risks to the health of Lisbon residents, Welch shut down the chlorinators. There were no problems for one full year. Then came unusually heavy rains and snowmelt last week that resulted in the flooding of low-lying areas.

The health risks from chlorine involve byproducts that result when chlorine and carbon compounds mix.

In the 1970s, scientists discovered that chlorine, when added to water, combines with organic matter such as vegetation and algae. This combination forms Trihalomethanes (chlorinated by-products), or, THMs. <snip> THMs have triggered much debate in the scientific world. Some studies have found a clear link between THMs and increased cancer rates – particularly for bladder and colorectal cancers. There is also concern that these byproducts may cause reproductive problems such as miscarriages. Other studies find no harmful effects from THMs. Through recent changes in national drinking water quality standards, the EPA requires that water treatment systems of cities and smaller towns begin to reduce THMs levels in the water supply. Ultimately, speculation on this matter is secondary to the very real threat of waterborne bacteria, viruses, and parasites.

In the late 1980s, officials in Peru began shutting down their chlorination plants. In 1991, cholera broke out, spreading through the now unchlorinated water systems. The epidemic would eventually strike some 731,000 people, killing 6300 of them.

But they had no THMs in their system when they died.