Gray PEX or Polybutylene?

I inspected a townhouse that was full of gray water pipes which everyone tells me is polybutylene. However, it was recently installed and the unlicensed plumber (!) says it was PEX. There is a gray PEX on the market. Does anyone know how to tell the difference?

Did you get a pic of the markings on the pipe? Post it for us to see.
No markings? If no markings, I call it out as unknown. I have seen PB and PEX with no markings. When in doubt, call it out… but do it PROPERLY or you could ‘burn’ yourself!

Thanks. No markings. See pics

Looks like PB to me. And if he is unlicensed, he isn’t a plumber, he is a handyman.

Looks like PB to me as well

Good Website on the subject above here;

The pipe is clearly PB, and wasn’t recently installed.


At least a few years judging from the top picture. More passing time means more prone to leaks

It is clearly Poly B

It is poly and whoever did it was not a plumber. The improper drain line connection is a nice touch! I wonder how long it has been leaking into the wall?

Thanks everyone and thanks for pointing out that this was not recently installed!

Phil Wise

I saw an attic full of gray pope yesterday. It had been ripped out and replaced with copper. And then just left in the attic. It was a 1982 build.

Agreed. They don’t make grey pex - if only to avoid confusion. They also stopped making Poly B… I am gonna say about 15 years ago? Maybe more. They still make the adapters for it, so you can switch it over to PEX. If you see it, flag it.
However, it should be specified that most problems with Poly B had more to do with the plastic fittings - the brass or copper ones were better. Not great, just better. Flag it anyways as a source of concern.

A touch of history on the subject here;