Plumbing – how to repair leaking water main

plumbing

So here's the situation. I've got a water main that is gravity fed from a spring into a cistern in my basement (and from there pumped to a pressure tank and the house). The main, black plastic and presumably either 1" or 1 1/4" HDPE is leaking somewhere very close to the stone foundation wall. I'm guessing that abrasion by movement of the stones over time or even during the initial installation by the previous owner maybe caused this. In any event, it's causing water to slowly seep through that section of the foundation and into my dirt basement.

Would like to avoid digging right near the stone foundation as well as disturbing the foundation in any way. That would be both costly and risky.

I've come up with what I think might be a decent plan – dig out farther away, maybe 20 feet from the foundation, and feed a new narrower pipe (with OD < ID of current pipe through the old one. This has the advantage of using the old one as a protective sleeve to prevent further damage. The disadvantage would be a slight decrease in pressure of the main, but because of the cistern I dont think this is a problem (probably why the cistern was used to begin with).

Here's a schematic main:

My questions are:

  1. good idea of bad idea?
  2. Do I use HDPE or PEX as the replacement material? Depending on the current pipe ID I may be forced to use PEX since it looks like HDPE is hard to find in narrow diameters.
  3. How to i make the best possible connection? I can't quite figure out the best way to join HDPE to PEX… would they both use similarly sized barb fittings and clamp rings? Would compression fittings be better?

Best Answer

You should (as per comments) verify that the pipe is even leaking. If it's not, you can do all this work and still have water entering the basement. It may be a lot simpler ("slow leak") to simply arrange a nice ditch ("dirt basement") to direct the water to a convenient exit point.

You should make a serious effort to accurately measure the 2" long stub of this pipe you can see - You have described it as 1" or 1-1/4" and as 1" OD (which is not 1" PE well pipe - that has an ID of 1.049" from most makers.) It may be easier to examine at the spring end, if it's the same type of pipe all the way.

If you do have 1" pipe, you can use 3/4" PEX (0.875" OD), which would be far better than 1/2" PEX, even for 20 feet.

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