Underground leak ... and it's polybutylene (install, room, plumbing, leaking)

[Narfcake]

So a little over a week into home ownership, and the fun keeps on coming.

Anyways, the underground leak was a known condition in the purchase ... I just didn't expect it to be PB (Blue Max) piping. Everything I've read is to replace it - the two pinhole leaks right now ... "are just the beginning", as some say.

The thing is that it's 1" PB, possibly even 1-1/4", even though the city water meter is only a 5/8" connection. Any reason why I can't just install a new run of 3/4" PEX inside the existing PB piping, as so I don't have to trench the entire front yard, which is on a partial slope?

[al_roethlisberger]

Well, to tell you the truth, that might be a good solution to use the old PB as a conduit/chase out for your new PEX.... if it will fit. You'll have to check the ID of the PB and OD of the PEX. Depending on how tight a fit and how long the run, you might have a hard time pulling it though as the PEX may bind up inside the PB. If you have the time/patience it might be worth trying though.

Two things might help(already assuming it is physically possible):

1) Blow(with compressed air) a pull cord through the existing PB line so you can pull and push the PEX through. Just trying to push the PEX through is almost guaranteed to bind up at some point.

2) Get some cable pull "grease" and lube the PEX as it goes into the old PB "conduit". You can get this in the electrical section of your favorite big-box home improvement store, or an electrical supply.

This may all be academic though if:

1) It is somehow not code compliant(not sure why it would be, but...)

2) The PB has a lot of hard water deposits that make it no longer clear and round inside

You might also want to just double check with your local building department to make sure there isn't some odd code issue too. I can't imagine why it would an issue, but you never know.

I have an old galvanized 1-1.5 inch supply line coming from a 5/8 meter... who knows why.... but I've had the same possible idea if/when it starts leaking versus digging it up. It is about 80 years old, so it is probably due

Al

[Narfcake]

Reading more into it, the only aspects I'm foreseeing is lack of volume and/or too much pressure loss - I need do some hydraulic calcs for that.

Diameter wise, it'd be OK. PB piping has a thinner wall/larger ID than comparably sized pipes (hence the problems too); the 3/4" PEX is 7/8" diameter, so on that aspect, there's room.

[Barking Spider]

Sounds like a great idea to me. Should be no problem with flow, since you are really limited by the smallest size pipe in the system, and that's probably the 5/8" at the meter.
How hard it will be to fish it thru the poly is dependent on how long a run it is. The hardest part might be if you start at the meter, since the space is pretty limited working in that meter hole. I would probably start at the house end and push it toward the meter. Of course, that assumes you have pretty good working room under the house or in the basement (or where ever the main pipe comes in).

Good luck.

[Narfcake]

Running the numbers, flow/pressure would've been OK; static pressure in the area is over 80psi.

Alas, the idea won't work, as going by the 2007 California Plumbing Code, Table 6-6, 3/4" allows for 20 fixture units ... and I have 29 to account for.

Time to start digging, I guess. Lay some 1-1/2" "conduit" for 1" PEX, just to make any potential servicing in the future much much easier.