Tuesday, August 23, 2016

MLGW Explains EPA Requirements For Sample Testing

In an effort to determine if municipal water systems have an effective corrosion control program for potable water, EPA requires that water samples from 50 homes be analyzed by MLGW for lead and copper once every three years. Twenty-five (25) are to be homes with lead water service lines/plumbing. The other 25 are to be copper service lines with lead solder. The list of 50 is to be picked from a larger group of about 100 addresses. The same list of about 100 addresses is to be used each time, every three years. The group of about 100 addresses is called the pool of sites.

Water service lines include the utility owned water line between the water main and the water meter, and the privately owned line between the water meter and the house. Some homes even have lead plumbing within the home.

The purpose of this exercise is to see how well our corrosion control system is working. We have a list of 112 addresses that was established in 1992 when the regulations took effect. 57 of those addresses are designated as lead services. The other 55 are copper.

EPA regulations suggest several methods for coming up with this list including plumbing inspector records, age of construction, etc. My staff is confident that our list was established in accordance with EPA regulations. Verification of pipe material at these addresses does not require digging the line up to verify. In fact the EPA regulations recommend meter readers do any physical inspection.

The easiest way to do a physical inspection is to look in the meter vault and see what type pipe is going in and out of the meter vault. This year we looked at all of the original 57 addresses designated as lead. Physical inspection, primarily looking in the water meter vault, verified that at least 32 were lead. This does not mean that ONLY 32 were lead. Many times the service line pipe material changes between the meter and the water main or between the meter and the house. So how do you determine if a water service line is made of lead if you cannot physically see lead?

EPA states that you can also confirm the presence of a lead service line by results from analysis of the water. Since 1992 a total of 50 of the 57 “lead” addresses have tested positive for the presence of lead. So we know there is a lead pipe somewhere between the water main and the faucet.  Usually the amount of lead found is less than the EPA action level. In fact as long as less than 10 percent of the samples contain less than 15 parts per billion(ppb) lead, then the water system meets EPA criteria.

So what happens if the analysis of the samples finds more than 10 percent exceed 15 ppb lead? Typically when this happens EPA may require the water utility to undertake an effort to identify which homes have lead water lines throughout the entire service area, Initiate a program to eliminate lead water lines or improve the corrosion control efforts.

In the case of MLGW we already have a great corrosion control program. In addition we are already actively performing physical inspections of water service lines on a mass basis in order to try to identify what water service lines are made of. Finally we are already actively replacing MLGW’s lead service lines and intend to budget more money for this effort next year so that we can replace the lead service lines at a faster pace.

MLGW estimates that out of 254,000 homes and businesses in our service area that about 25,000 have lead service lines. Most of these homes are within the Parkways or just outside the Parkways. MLGW has an interactive map that although not 100% accurate provides information regarding where lead service lines may be located. Our goal is to replace all of these lead service lines within the next ten years.

MLGW offers free testing of anyone’s drinking water. If a customer has measureable concentrations of lead in their water, then we provide tips on how they can minimize exposure to lead in their drinking water.

MLGW is confident that we are in compliance with the letter and spirit of the EPA regulations. Our water is in fact the best drinking water in the country. 

You can find more information in our Water Quality reports. The Lead Service Database can be found here.

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