Can levels that exceed the standards be attributed solely to having lead solder in indoor plumbing?
No. On the Island of Montréal, although lead solder in indoor home plumbing can cause lead to dissolve in tap water, it does not result in lead levels exceeding the standard of 10 µg/L after the water has been running for at least 5 minutes. In fact, a few years after this type of solder is installed, a protective film forms inside the pipes that limits dissolution of lead solder in the water. Moreover, the material used to solder pipes has contained almost no lead since 1989 (less than 0.2%).
