You've seen plenty of white PVC pipes before, but the gray-blue ones in your basement are a new encounter. And sadly, finding gray-blue pipes in your basement is not a good thing. If you're sure the pipes are actually blue plastic, and not just metal or white PVC pipes that have been painted, then the pipes are probably made from polybutylene, a plumbing material that is known to cause some pretty big issues.
What is polybutylene?
Polybutylene is a type of plastic. It's not all that different than PVC, but it is just different enough. Plumbers loved using polybutylene pipes between the 1970s and 1990s because the material was cheap and easy to work with. They used it mostly for water distribution pipes — the ones that carry clean water into your home and to your faucets — rather than for drain pipes.
What is the problem with polybutylene?
Sometime in the mid-1980s after the early polybutylene pipes put in homes started to age, some of the pipes began to fail. They did not fail by slowly developing leaks, as is typical of copper and steel pipes. Rather, they would suddenly burst. As you can imagine, this caused extensive water damage to homes. If the homeowners were not present when the pipes burst, water could spew all over the home for hours before anyone was aware.
What was done about the problem?
At first, plumbers assumed the issues with polybutylene pipes had to be a fluke, but it soon became clear that there was something worse at play. In the 1980s, a group of homeowners sued the manufacturers of polybutylene pipes, and slowly, it came out that this material was not a safe plumbing option. By the early 1990s, plumbers had stopped installing polybutylene pipes completely.
What should you do about your pipes?
Plumbers have been recommending for years that anyone with polybutylene pipes have them replaced before they fail suddenly. Obviously the previous owner of your home overlooked the severity of this issue, but you do not have to do the same. Have a plumbing contractor come examine the pipes and ensure they are, in fact, polybutylene. If they are, the plumber can replace the pipes with some made from copper or PVC, both of which are much safer and less prone to bursting.
If you find blue-gray pipes in your basement, this is not a good sign. Make sure you act quickly to avoid serious water damage.