Working with slab houses

[ewoltk]

Our house has a plumbing issue of gravel in our water.* (We are not on a well.) Water from city to house is clear. Question: if there is a break in the plumbing pipes, are those pipes inside the concrete slab or under it? And, would it make more sense to just run new piping than rip up concrete inside house to replace pipes?

*gravel starts up again each spring when we begin using sprinkler system.

[Slaughter Construction Co]

I can't tell you how the gravel gets into your water system, but I doubt that your pipes are in your slab. I don't know how old your house is, but as long as I have been around the building business (50+ yrs.)no code I know of ever allowed that.

I have had gravel get into my water system before. I lived at the bottom of a hill and every time the water main at the top of the hill broke I would get grave from the repair. It would settle at the bottom of my water heater. You might check to see if you have gravel accumulating in your W.H.

I doubt that gravel is getting in your pipes under your house. If you had a opening large enough for gravel to enter (and it couldn't while under pressure) you would likely see water coming out somewhere and your water bill would be unusually high.

Does you sprinkler system have a back flow preventer?

[GregBradley]

In my area of CA, virtually everything is built on a slab. Houses we built in 1980s did not allow pipes in slab. I've worked on some houses built in the 1970s that were built with the pipes just laid on the bottom of the form for the slab. That means that the bottom of the pipe is in dirt and the top in concrete. Really poor work that clearly didn't meet code when built.

They go in trenches filled with sand UNDER the slab and then come up through the slab with plastic sleeves. Most of these are failing by now and are replaced overhead.

Neither of these will get you gravel in your water. The water pressure will force the water out, giving you a big water bill but not dirt flowing back in. I think Slaughter nailed the problem.

When I repiped my own house, I put an RP Valve on the water supply to the sprinkler system just like you would do on commercial buildings. That prevents dirt, etc from coming back in to the house water supply. If you are sure the gravel is tied to sprinkler use, I would suggest some form of backflow prevention. I would think the most likely place for gravel to enter would be upstream from a water supply repair.

[Dutchman]

Not only a backflow preventer between irrigation and domestic, but also, a sub meter.

Domestic use is billed at X rate in your area, irrigation will be about half of X because you're not running it back through the public sewer.