House Project: Lead Filtering

I've mentioned previously that the lead filters clogged rapidly, so we had to put in additional housings for five micron and one micron filters to grab more of the crud first. So last week, I went up and took water samples, to make sure that we hadn't messed anything up. Remember that before putting in the lead filters, I had tested the water twice for lead, getting 15 parts per billion (the EPA action level) in the first test, and 37 ppb in the second test. That's part of why we put in the lead filters.

Well, interesting results! I had taken a water sample from inside the house (which runs through all the water filters), and a sample from the outside faucet, which runs straight from the water tank. I had the lab test the inside sample for both lead and iron, and the outside sample just for lead.

The inside sample was .26 milligrams/liter for iron--which is below the EPA action level of .30 mg/L. Good.

The inside sample for lead was <.002 mg/L for lead--which means unmeasurable. That's good, and exactly what happened when we first put in the lead filters.

But the outside sample--which has no filtration at all--also shows <.002 mg/L for lead. It appears that whatever was putting lead into our water supply a few months back isn't putting it there now.

Several possibilities:

1. The lead was a contaminant that was introduced into either the well or the water tank during the construction process--and all of this elaborate filtration was unneeded, as the contaminated water has been used.

2. The lead in the well water is dependent on changes in pH, temperature, or underground water flow rates or directions. In that case, the lead may come back.

I think for the moment my plan will be to continue to test the lead content of the water (unfiltered) every month for the next year. It only costs about $10 to have the lead test run. If the lead reaches a measurable level again, I will have to assume that I need these rather expensive lead filters.

If lead never reappears in the unfiltered water, when the lead filters finally clog up, I can just remove them, and allow the system to operate with one less restriction on water flow. Of course, I will still have the water tested every six months for lead, coliform bacteria, and iron.

Last house project entry.