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Water Main Blues

CapnJohn's picture

What is the accepted attitude towards placing a water main supply line through a footer then under a slab to feed the house?

We have a 20-year-old berm house (so we are living on the slab) with the main supply line running under the slab.  The slab floats free of the footers. (That's a whole other discussion.)  We have develped a leak (800 gallons a month) between the main valve at the road and the main shutoff in the house.  Question is:  Is the leak in the plastic pipe from the road to the house entry point or from the house entry point under the slab to the valve?  About 20 feet of schedule 40 PVC runs under the slab.

BTW:  No soil here.  Just clay and rock.

Any thoughts on this rather immediate issue?  We may be excavating soon.

Thank you.

Capn John


Capn John

That'll be hard to pinpoint, (post #207446, reply #1 of 12)

That'll be hard to pinpoint, since there's no way to isolate one portion from the other.

As a guess, the most likely place might be where the pipe passes under the footing, due to the possible settling. PVC is fairly brittle, and it wouldn't take much movement to crack it.  You're losing only about a gallon per hour, so it's not a very big leak yet.

Another possibilty is if there's a joint beween the schedule 40 PVC and some other type of pipe--you say "plastic", but if it's not also PVC, then there's a joint betweeen the two, which would be far more likely to leak.

Damn hard I'd say (post #207446, reply #2 of 12)

From what I've learned, using PVC is foolhardy, especially where it passes through the footer then under the slab -- two different motions.  We have uncovered all the joints that we are aware of with no revelations.  800 gallons may not seem like a lot, but we are paying for it.  Paying for wasted water.  As a tree-hugger, that bothers me.

Thanks for the feedback.




Capn John

capn (post #207446, reply #3 of 12)

Where's the meter?  Evidently up by the road, in order to know that you are using water b/4 it gets into the house shutoff.

Where's the house shutoff?

How long can you be w/o water?

A Great Place for Information, Comraderie, and a Sucker Punch.

Remodeling Contractor just outside the Glass City.


Meter location (post #207446, reply #5 of 12)

The meter is located in a pit by the street.  300 feet uphill to a hydrant in the yard then 50 feet to the house.  20 feet into the house, under the slab, the line pops up.  There is a shutoff right there.

In the test, we closed the valve in the house and at the streeet.  Pressure dropped.

the big question is:  do we replace just the tubing from the road to the house, or do we replace the works?

Thanks for your input.



Capn John

Obviously, you could excavate (post #207446, reply #4 of 12)

Obviously, you could excavate and cut the pipe near where it runs under the footer, cap it, and see if it still leaks.

Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

And excavate we shall, unless . . . (post #207446, reply #6 of 12)

it proves cost ineffective.  One consideration is the age of the pipe.  I know the line from the road was cheap, thin wall tubing.  The PVC under the slab must be very brittle by now.  It might just be worth the expense to replace it all and be done with it.

No price on peace of mind.

Thank you



Capn John

So, have you exposed all the (post #207446, reply #7 of 12)

So, have you exposed all the joints at the hydrant and checked that the hydrant itself is not the culprit? And where the pipe meets the foundation? And what kind of plastic is the line up to the foundation, before it changes to PVC? Is is polyethylene? Even thin-walled polyethylene will last  a very, very long time--like the bread sacks they tell us will still be in good shape 200 years from now in our landfills. And, it's quite forgiving of any ground movement.

Buried PVC will outlast you or me so long as it's not subjected to stress from settling. Water utility companies and municipalities use it for their mains and within water treatment facilities. It's a great product if it's protected from UV and from mechanical damage.

I noted the small amount of leakage because it indicates something other than a failure of the PVC due to stress, which would likely crack the PVC and result in a much greater loss of water. One gallon/hr seems more like a leaking joint to me.

Good Info (post #207446, reply #8 of 12)

Thank you.  Though local plumbers are telling me that PVC gets brittle around here.  The ground is very acidic due to the clay.  Last fitting that went bad was a galvanized Tee.  Almost completely eaten away.

Regarding CPVC fittings in the house:  When making repairs the old CPVC just splits and crumbles.  It is very brittle.

One must remember that I live amongst hillbillys.  Everything was and is on the cheap without any concern for Codes and accepted trade standards.  the list of problems with this twenty-year-old house is longer than your arm.

Even today, local contractors are at least 50 years behind the times. Actually that applies to everything.  The locals are under-educated, ill-informed and generally dump as stumps. someone I know just had a small house built, 2x4 construction, and teh builder installed R-19 in the walls because packing in more fiberglass will give you more insulation value!  they built the house on a bed of gravel using 4x6's as skids.  The floor is now like the rolling hills of Scotland.

I have to be very careful here about choosing contractors.


Capn John

I have to be very careful (post #207446, reply #9 of 12)

I have to be very careful here about choosing contractors.

And, be careful of who reads your posts and who hears yourr opinions, you don't need neighbors for enemies!

I already have more enemies . . . (post #207446, reply #11 of 12)

than friends.  I have been hear four years and have only found two people with similar attitudes.  Most of my neighbours think me an idiot because I don't do things the "country way".  Sorry, I refuse to leave a refrigerator on my front porch for years.


Capn John

water supply lines (post #207446, reply #10 of 12)

Where i am located frost goes down 3 ft in winter so one has to allow for it in installing supply lines

I always install heavy duty polyethlene supply lines using nylon fittings & double clamp all joints off setting the stainless worm clamps (if ground is very acidic use marine clamps ) ( marine clamps are all stainless , not just the band )

If you have frost bury line in sand 6"" then put 1 1/2 "" styrofoam 12 "" wide over it  plus some more sand then backfill

I live in a rocky area so digging 3 ft with a hoe is a joke normally

I have never had to go back on supply line in the last 35 yrs & some were only down 1 1/2 ft

Great info, (post #207446, reply #12 of 12)

Dude.  I have always believed beding the best line (200psi) in sand with XPS on top is the best way to go.  And coming from a marine background, everything is double clamped!

Funny you should mention it, cause the line entering the house is only 1-1/2 feet deep.  I excavated there first assuming a crack due to freezing, but it was not leaking, so okay.

After much conversation and conjigation, I believe we are giong to opt for a complete replace of the entire line.  New heavy duty tubing from the street to the house, then come into the house through the back CMU wall three feet below grade.

eliminate risk and be happy.

Thank you for you input


Capn John