Non-harmful coliform bacteria detected in the system

The Rivergrove Water District began adding chlorine to its entire drinking water system Oct. 24 following discovery of a “non-harmful coliform bacteria in the system.”

Originally, only a portion of the water (the “upper” pressure zone) was disinfected with chlorine. However, the decision was made Oct. 24 to add chlorine to the entire system. The media was notified about the decision two days later on Friday, Oct. 26.

According to district officials, “Our water system recently violated a drinking water standard. Although this incident was not an emergency, as our customers, you have a right to know what happened and what we did to correct this situation. We routinely monitor for drinking water contaminants. We took 15 samples to test for the presence of total coliform bacteria during October. Six of our samples showed the presence of total coliform bacteria. The standard is that no more than 1 sample per month may do so.”

Officials said “Coliforms are bacteria, which are naturally present in the environment and are used as an indicator that other, potentially-harmful, bacteria may be present. Coliforms were found in more samples than allowed and this was a warning of potential problems.

“Usually, coliforms are a sign that there could be a problem with the system’s treatment or distribution system (pipes). Whenever we detect coliform bacteria in any sample, we do follow-up testing to see if other bacteria of greater concern, such as fecal coliform or E. coli, are present. None of these were found in follow up testing. However, we are still finding total coliform bacteria in the system. We anticipate resolving the problem before the end of November.”

System users are being told they do not need to boil their water or take other corrective actions. However, “if you have specific health concerns, consult your doctor. People with severely compromised immune systems, infants and some elderly may be at increased risk. These people should seek advice about drinking water from their health care providers.”

Enough chlorine is being added to the water to maintain a chlorine residual of 0.2 to 0 parts per million, equivalent to about 1 drop in 44 gallons of water. Officials said a “typical swimming pool would have anywhere from 2.0 to 4.0 ppm of chlorine residual, roughly 4 to 10 times higher than typical drinking water.”

Some water users may be able to smell or taste a small difference, it will not be as strong as what is used in swimming pools, officials said.

For many customers, there will be no noticeable change in drinking water quality.

However, others may not be so lucky.

“Chlorine has a distinct odor and may affect the taste of the water,” officials said. “However, these changes do not affect the safety of the water. During the initial disinfection implementation period, some customers may notice a discoloration of the water as the chlorine reacts with any organic and inorganic residue currently in the distribution system. Should you experience dirty or discolored water, please contact the district at 503-635-6041 for assistance.”

Officials suggested setting “a pitcher of water aside overnight (on the counter or in the refrigerator). The chlorine dissipates over time, so the smell and taste should be less noticeable. Inexpensive pitcher or faucet filter systems that remove chlorine are also available at home improvement centers.”

Additionally, special precautions are suggested for water used in home dialysis systems, in aquariums and for aquaculture as well as for restaurants and grocery stores that have aquatic life, such as live lobster tanks.

Officials said their “plan of action” includes:

• Reservoirs are being inspected and cleaned.

•Continue to do hydrant flushing to move fresh water throughout the system.

• Chlorination of both the upper and lower system has begun.

More information can be obtained from:

•DJ Ezell at 503-635-6041 or at the district office at 17661 Pilkington Road.

•Oregon Health Authority, Drinking Water Program

•Environmental Protection Agency

•Rivergrove Water District

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