This month's water treatment topic.

EPA researchers report that scales and films in drinking water supply pipes can accumulate and leach high levels of contaminants

According to the Water Quality Association, U.S. Environmental Protection Agency (EPA) personnel reported disturbing drinking water distribution system revelations at the Inorganic Contaminants Workshop sponsored by the American Water Works Association in early February.

Agency field engineers have been discovering that “regulated inorganic and radiological contaminants present in source water above detectable [analytical detection levels] but less than the safety standard, can accumulate in distribution systems to a significant number of times above their respective standard, and that this is a largely unknown, unexplored and universal phenomena.”

In other words, though the water leaving a municipal treatment plant complies with all EPA criteria, events occurring in the water distribution system after water leaves the plant can lead to significant spikes in contaminant levels.

Case histories were reported in which scales and biofilm that sheared off or otherwise leached from pipe walls have caused drinking water levels exceeding tens and thousands of milligrams per liter for iron and copper and exceeding hundreds of micrograms per liter as well for arsenic, lead, zinc and manganese - well above levels considered to be safe for consumption.

This same phenomenon occurs with radium and causes two distinct problems:

1. Radium in pipe deposits far exceeds the Safe Drinking Water Act maximum contaminant level of 5 picoCuries per liter.

2. Radium decays to radioactive radon, which is released into the flowing water supply.

One EPA researcher reported that scales in household plumbing literally could cause the home's water pipe system to exceed the federal government's toxicity characterization leaching procedure (TCLP) limits - making those deposits, by definition, a hazardous waste.

Another meeting report noted a related adverse reaction in household plumbing that actually is being created by the increasing use of chloramination for public water system disinfection.

Chlorine typically dissipates from chloramines as water resides in home water pipes. This auto-decomposition creates ammonia, which then can change to nitrites. The nitrification process lowers water pH in low alkalinity waters - which can lead to iron and copper corrosion in home plumbing.

WQA's technical director, Joseph F. Harrison, says, “The Water Quality Association supports the need for further research into the public health significance of these discoveries. We also urge new research into all possible remedies, such as more effective central treatment and control schemes and the feasibility of using of point-of-use and point-of-entry water treatment approaches inside the home to provide safeguard barriers for consumers' public health protection.”