Pipe that lives in a hard place
A water line under a slab is surrounded by soil, gravel and concrete, carries water under pressure all day, and on the hot side heats and cools many times a day. It cannot be inspected or maintained without opening the floor. Much of Anaheim Hills was built from the 1970s onward, so many of these lines have now been in the ground for decades.
Plumbers talk about a handful of causes again and again. The honest answer for any single leak is that the cause is a judgment made after the pipe is exposed, and sometimes not even then.
The usual suspects
| Cause | What happens | What it can mean for the rest of the line |
|---|---|---|
| Abrasion | Pipe rubs against concrete, rock or another pipe as it expands and contracts | Other contact points along the same run may be wearing too |
| Fittings and joints | A soldered joint or bend under the slab fails | May be isolated, or a sign of how the line was installed |
| Internal corrosion | Water chemistry slowly thins the pipe wall from inside, sometimes as pinholes | Often affects long stretches of pipe, not one spot |
| External corrosion | Soil conditions or contact with other metals attack the outside | Depends on the soil along the route |
| High pressure | Pressure above what the system needs adds stress to every joint | Fixable at the pressure regulator, which helps the whole house |
| Ground movement | Settling or shifting soil under a graded pad stresses the pipe | Worth mentioning to the plumber if the house shows other cracks |
Water chemistry in Anaheim
Anaheim's water is a blend of local groundwater and imported water and is on the hard side. Hard water leaves mineral scale, and water chemistry is one of the factors discussed in pinhole leaks in copper, but the science is not settled and many other things matter, including the original pipe quality and how the water flows. Questions about the water itself are best taken to the city's utility, which publishes water quality reports.
Things you can check that relate to causes
- Water pressure at an outdoor hose bib with an inexpensive gauge; ask a plumber what range is appropriate for your house
- Whether the house has a pressure regulator near the main shutoff and roughly how old it is
- Cracks in the slab, walls or driveway that suggest the ground has moved
- Any record of earlier leak repairs and where they were
Ask the plumber who exposes the pipe
If the slab is opened, you have a rare chance to see the line.
- What does the failed section look like inside and out?
- Does the pipe on either side of the leak look sound or thin?
- Was the pipe touching concrete or rock where it failed?
- Would you expect more leaks on this run, and why?
- Can I keep the removed section of pipe?
Common questions
Did something I did cause the leak?
Usually not. Most under-slab leaks come from age, installation and conditions around the pipe that a homeowner could not see or control.
Will a water softener prevent slab leaks?
A softener changes water hardness, but the causes of leaks are varied and not all relate to hardness. Ask a plumber or water treatment professional for advice specific to your house rather than buying one only to prevent leaks.
Does high water pressure matter?
Excess pressure adds stress to pipes and fixtures throughout the house. Having it checked is inexpensive compared with a leak repair, and a plumber can tell you whether the regulator is doing its job.
General information for Anaheim Hills, not a quote or professional advice. In an emergency, call 911.