Very occasional thoughts concentrating on the useful.

Sunday, July 02, 2006

Time to clean my aerator

It just watched an interesting video lecture (real player 56K, real player 350K, Windows media 56K, Windows media 350K) from Princeton's online lecture series about government incompetence in making sure your drinking water isn't contaminated by lead.

The talk is by Marc Edwards, of Virginia Tech.

There were a few non-obvious points:

0. It's a good idea to have your water tested yourself, not to count on the government or water company to do it for you. Make sure the testing agency acidifies the water to a pH of <1.8 to dissolve any particulate lead in the water. Note that your stomache acid will do this.

1. Flakes of lead solder often get stuck in your faucet's aerator, the little screen that screws onto the nozzle. When you turn on your water fast you can often get little particles of lead in your water. Hence if you test your water for lead then you should turn on the nozzle fast. If you drink from the faucet then you should turn it on slowly.

2. Lead solder is the most common source of lead in water, even more so than lead pipes. When lead solder is applied to copper or brass you often get a galvanic electrochemical reaction that causes the lead to enter the water.

3. It's a good idea to unscrew your aerator and see if there's metal there, and clean it out.

4. You may also want to flush the pipes if the water has been standing in them for a long time.

5. Lead in water does NOT come from the water main. It comes from the pipes that bring water from the main.

Anyway, it was a good lecture and I'd recommend checking it out.


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