Schedule 40 PVC for water supply line

[feckman]

Hello,

I'm a homeowner living in Upstate, NY, and I live on a cul-de-sac with 11 other houses on it. This road is around 1/4 mile long with each house having around 8 - 10 acres. The topography is a very steep hill -- more of a talus slope from an adjacent rock escarpment. There is very little water "up the hill," but there is an artesian water supply at the bottom where everybody has their wells (each house has a small "well lot" where there is seperate electrical service and individual pumps). Water lines then run up the hill to each of the houses.

All that said, when the road was built and the lots created in the mid-80's, schedule 40 PVC was used for the water supply lines. Since that time, there have been 40 to 50 breaks in the lines over the years. They are run literally right next to each other, and very often a break in one line will cause additional breaks in adjacent lines.

My question is this: is (was) schedule 40 PVC "legal" to use in water supply lines at that time? Over the course of the few years we've lived here (and the multiple breaks we've suffered), every plumber we've had working on the lines was surprised to find schedule 40 PVC used in such a configuration.

Thanks in advance for any information!

--Jim.

[Jerry Peck - Codeman]

Hi Jim,

Yes, Schedule 40 PVC was, and is, allowed for use as exterior water service lines.

There are several conditions which are required to be met for water service lines regardless of what material is used, some of which could lead to the breaks and leaks you and your neighbors are experiencing.

Some of the required conditions regardless of the material used are:

- All trenches for the piping are required to be excavated such that the fill under and around the piping is "clean fill", i.e., no stones, rocks, gravel, tree debris, nothing but dirt or sand ... and that dirt or sand contains nothing which could damage the pipe.

- All piping is required to be either below frost depth or protected from freezing in an approved manner.

- All piping is required to be laid straight with no bends in the piping, changes in direction are only to occur at joints. An exception to this would be flexible water service piping such as polybutylene, PEX, and similar flexible piping.

The potential for problems with any piping material increase, and dramatically increase when associated with PVC piping, if any of the above conditions were not done correctly at the time of installation. The potential for problems is even greater when any combination of the above conditions were improperly done at the time of construction.

Most leaks with water piping are a result of installation problems (other than galvanized steel piping which eventually leaks from rusting out, or copper piping which leaks from corroding out because of harsh - acidic usually - water). Those installation problems can be caused by the installer of the plumbing piping or by installers of other systems who come along later.

Below is an example which happened to me and is related to your problem and question.

We had a house in South Florida which developed a leak, it first showed up as an ever increasing usage of water, sometimes when I would look for evidence of leakage at the meter (the little flow indicator turning slowly) I would see it and sometimes there would be no movement in the flow indicator, that leak amounted to 10,000 gallons over a 3 month period - that's like filling a small swimming pool.

Tracking down an intermittent leak is always troublesome. As the leak progressively got worse I finally found some water at the property line with our neighbor, where our water lines where also run together as yours were. I dug down at the location where the water was and found a rock which had, over time, pressed against the top of the PVC water service pipe, scratching into the pipes surface, weakening it, then allowing it to crack.

Only one rock in the large hole I dug down to find and repair the leak, and that one rock was on the pipe, the rest of the fill was "clean fill" as required - that one rock, which was not allowed to be there, but which the plumber apparently did not think it was worth removing - caused that leak 28 years later.

What caused the leak? "Installation error". The plumber did not use "clean fill", or, they used "clean fill" but allowed other debris to mix in with it, either way, had it not been for that "installation error" that water service pipe would not have cracked and leaked.

Codeman