Lead & Copper sampling for drinking water systems is very unique in how the samples are taken; how they are reported; and how the data is used.
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| Lead ©2011 Inorganic Ventures, Inc. |
For the most part, lead and copper samples are collected every three years. But, unlike the rest of the samples we are required to take, lead & copper samples must be collected by the customer, since they can only be collected from a tap inside the customer’s home. The tap it is collected from cannot have been used in the previous 6 hours, there can’t be a water softener on the system, and the customer must collect a full liter of water for the sample to be valid. Needless to say, asking your customers to do all of that can be problematic. Samples have to be collected this way because the lead & copper regulation is designed to test premise plumbing, and most lead & copper in peoples drinking water comes from either home fixtures, lead solder in old plumbing, or lead service lines. Every customer who provides a lead & copper sample receives a letter detailing what the results were for the sample taken from their home, as well as a lot of additional information about these elements that is mandate by the U.S. Environmental Protection Agency (EPA).
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| Copper ©2011 Inorganic Ventures, Inc. |
There isn’t really a pass/fail for individual lead & copper samples, and there is no Maximum Contaminant Level (MCL) for this type of sampling. Instead, the regulations have an Action Level (AL) of 0.015 mg/L for lead, and 1.3 mg/L for copper. If the 90th percentile level for the lead & copper samples taken is above the AL, then the regulation requires that the water system take corrective action. Now, what the heck is a 90th percentile level? The 90th percentile means that 90% of the samples are less than that level, and 9% are greater. You determine the 90 percentile level by multiplying the number of samples you take by 0.9; so if you take 20 samples, then sample 18 is your 90th percentile sample. Then you put all the samples in order from least to greatest, and the value of your 18th sample is your 90th percentile level. Phew! Statistics makes my head hurt.
If a system exceeds the AL, then there are certain actions they have to take. These include a public education program about the health effects of lead & copper; implementation of corrosion control in the distribution system; and a lead service line replacement program where applicable. The health effects of lead include neurological damage in children, as well as high blood pressure and reproductive problems in adults. Excessive copper can cause liver and kidney damage in children, and various problems of the digestive system in adults.
If you would like to read more about the lead & copper rule, go to EPA’s web site at this address: http://water.epa.gov/lawsregs/rulesregs/sdwa/lcr/index.cfm
