Lead-tin solder ban and plumbing failures (1978)

If you actually look at how much lead we've used over the centuries — they were using lead and refining it into lead metal back 5,000 years ago. The Romans had lead mines and used it for coinage and other things. Then the British used to use it, and we used to use it. When I bought my house forty years ago it had the lead pipe in the basement, and they used to put all the water through the lead pipes. Now people get all upset about having lead solder in the copper pipes. I think it was 1978 or so they outlawed lead in solder for copper pipes, and now by law if you read your water bill every year they have to send you something telling you what the lead content is in the water that you've been drinking.

Externalities of material selection. The 1978 ban shifted plumbers to 95-5 (tin-antimony) solder, which produced more leaky joints. Combined with Boston's hot-work fire-watch requirement (paid off-duty firefighter at sixty dollars/hour), this drove adoption of mechanical crimp-on copper fittings ("PEX-A" cross-linked polyethylene became dominant in new construction).

Does anyone know why we've gone from soldering pipe to using this crimp-on mechanical connector? Because too many plumbers burned down too many houses soldering pipes. The law now says, in the last ten years in Boston, you must have a fire watch. This is one of the externalities of material selection. They got rid of lead-tin solder in 1978 by legislation. So they went to 95-5 — ninety-five percent tin, five percent antimony, or some have a couple percent silver for strength.

Brief mention — Massachusetts outlawed lead-tin solders in 1978. Used as evidence of the regulatory shift away from lead in plumbing.

It turns out when you machine a leaded brass, the lead doesn't mix with the copper and zinc. It forms little islands, inclusions of lead. When you machine it, the lead heats up, melts, and forms a lubricant. You can machine leaded brass about five times faster than regular brass. So it's cost again. We used to use leaded brass, and we never thought the amount of lead leaching out of the water was turning all the children ignorant. Well, in fact it wasn't — it was genetics that made them ignorant. But mom and dad don't want to think the genetics made their children ignorant; they want all the lead out of the system. In 1978 Massachusetts outlawed lead-tin solders, and now they only have tin solders for making plumbing.

Sequence of plumbing material substitutions: lead-tin solder, post-ban replacement solders with worse joints, current swage-style mechanical fittings. Holman attributes the example to Eagar's home renovation.

Another example. Professor Eagar gave me this yesterday. He's having a renovation done on his house. Have any of you ever done any soldering, either jewelry or things like that? Everyone has plumbing, and years ago all the plumbing was joined together by lead-tin solder. Over time there were environmental restraints on the lead. You've probably seen all over the news, all the people up in arms over the lead in school drinking water — that's a result of the pipes having lead joints. And they probably actually had lead in the composition of the pipes, they're so old.