Question about Lead in Private Well / Water Supply
Q: I had a water test done on a private well. The results say that public water needs to have a lead level of 5 or less and that 15 is unsafe. Is there a different standard for private wells and her client’s well tested at 10? What does that mean and is it a concern?
Answered by Bob Schultheis, natural resource engineering specialist with University of Missouri Extension (his contact info here).
A: The MCLG (maximum contamination level goal) for lead is zero, and the MCL (maximum contamination level) is 15 ppb, above which is considered unsafe. I’ve not found any reference that differentiates the MCL for public vs. private wells. Testing before and after the “first flush” of the faucet will help determine if the lead problem is in the groundwater or in the plumbing. If the well tested at 10 ppb, no action is needed, but if they want to play it extra safe and the problem is in the plumbing, they can run the cold water faucet 1-2 minutes before using the water for drinking or cooking. It doesn’t hurt to bathe in lead-tainted water.
The following links may be helpful.
Basic Information about Lead in Drinking Water (EPA)
Lead in Tap Water (CDC)
Water Tests: What Do the Numbers Mean? (Penn State University)