Cast iron pipe was the staple for most homes built prior to the 1960s, although plastics have become more popular since. Cast iron plumbing lines above ground in a house does offer some advantages. Cast iron is quieter than plastic because it vibrates less, so you do not hear water running through the lines as readily. It is very durable and will not burn, which can be important in case of fire; however, unprotected cast iron installed as underground service lines can be corroded by water and minerals in the soil. To address that, some cast iron pipes made today are sheathed in a protective material. These are far superior to the old pipes commonly used into the 1960s.

Galvanized steel pipes were also common in homes through the 1950s. Like cast iron, galvanized steel is strong but susceptible to corrosion. Galvanized pipe is also more prone to clogging. The coating inside the pipe eventually wears off leaving the pipes vulnerable to rust and mineral buildup that can clog the lines with minerals and waste matter. The useful life of galvanized steel pipe is about fifty years.

Rigid copper pipe remains a popular choice today especially for hot- and cold-water supply lines. Flexible copper pipe is used for water supply lines to appliances such as refrigerator icemakers and dishwashers. Copper is durable and corrosion resistant. Copper pipe comes in different wall thicknesses. Underground lines should be run using copper pipe with the thickest walls. Even then, careful installation is called for. A dent in a water line can eventually wear thin from the constant flow of water and eventually open a small hole in the pipe.

Plastic pipes are corrosion resistant and can be used above or below ground. Plastic resists corrosion and is relatively easy to work with. Most common types include:

• • ABS (acrylonitrile butadiene styrene) – Black in color, ABS was the first plastic pipe used in residential plumbing. There have been problems keeping ABS joints together which has led some municipalities to disallow it in new construction. A failed joint beneath a slab will result in a costly slab leak. Also, ABS can deform when exposed to direct sunlight, so it is not suitable for all above-ground installations.
  • PVC (polyvinyl chloride pipe) – PVC is the more commonly used plastic plumbing pipe now. Colors indicate intended usage including white for drain lines and irrigation, blue for potable water, green for sewer water, purple for reclaimed water, and gray for electrical conduit.
  • CPVC (chlorinated polyvinyl chloride pipe) – Similar to PVC, but the chlorination process gives CPVC different physical properties. CPVC’s ability to withstand higher temperatures makes it more suitable than PVC for hot water lines.
  • PEX (cross-linked polyethylene) – The newest plastic plumbing pipe, PEX, is used as an alternative to PVC, CPVC and copper. It is flexible, cuts easily and uses compression fittings which makes PEX relatively simple to install, but it also has some drawbacks. Making secure connections requires some skill, and its flexibility can cause vibration and movement problems. If not carefully secured, PEX can be abraded by movement over structures such as floor joists and rafters.

Sometimes it makes sense to avoid digging altogether and reroute plumbing above ground. For example, if a short section of pipe is the problem, and it can be worked around by installing new plumbing lines, rerouting may provide a quicker and less disruptive solution.

In some cases, such as when a home’s plumbing lines are encased in concrete and cannot be reached without destroying the slab, it may be best to repipe the whole house. Water supply lines can be routed around the slab instead of beneath it. The plumber will determine where new pipes can be installed such as in walls, through the attic, closets and other structures that may conceal and protect it. In some cases, a little creative woodworking can add a new feature – such as crown molding – to hide the pipes. Water continues to run through the old plumbing while new lines are installed, so you do not have to move out while the work is being done. Then, the old lines are shut off, and the new ones are opened.

The shortest distance to the source of the problem may be straight down through the concrete slab, but that also may be the most disruptive and most expensive. Because of this, we cut through the slab when other options are not available or are less attractive for some reason. There is no one size fits all solution.

Likewise, foundation building and repair companies caution that not all slabs are alike. They are engineered for the location especially considering soil type and depth. Some slabs should not be cut into at all, although properly repoured patches are secure. Breaking through the slab has some serious disadvantages for homeowners. First, you must live somewhere else while the work is being done as the water is shut off, the noise from jackhammers and saws is deafening, and the dust in the air requires you to cover everything. In addition, the soil that is removed either is left in a big pile in your home while work proceeds or is taken out with wheelbarrows. The flooring in affected rooms usually must be replaced – it may be difficult or impossible to match some hardwoods or tiles, for example – and you will have added costs for lodging and meals. As should be apparent, breaking through a slab to repair a slab leak can also be quite expensive.

In our experience tunneling beneath the slab offers several benefits for homeowners:

• • You can stay in your home while work is in progress
  • The mess is kept outside of your home
  • It is often the least expensive choice

Most homeowners prefer tunneling if they have expensive flooring. Some of the flooring, perhaps a room or more, would be destroyed by breaking through the slab from the top. Some plumbers dig their own tunnels; others use engineers who do the digging and certify their work.

Structural integrity is vital to a plumber working in a tunnel that can extend well beneath a house. Tunnels are dug about three feet by three feet to allow adequate working space. Correctly replacing the dirt that was removed is essential. When the new plumbing has been installed and tested, we refill the tunnel with the soil previously removed. We dampen the soil as we go and use metal tamps to pound it firmly back into place.

Pipe lining, or cured-in-place-pipe (CIPP), has become a popular option for many homeowners because it involves no trenching and very little digging to gain access to the problem area. The concept is simple:  broken water lines can be repaired by lining the inside of a broken pile with an epoxy coating that dries and hardens to form a new pipe. It is worth noting that the CDC has raised health concerns regarding the cured-in-place-pipe method for repairing plumbing lines. Often, contractors that provide the service offer no warranty. Underground pipes that have become corroded, have holes or cracks are the main candidates for this type of repair.

First, a cutting tool removes debris and buildup, then the line is rinsed. A resin-coated liner is placed in the pipe along with an inflatable tube, and air pressure presses the liner against the inside of the pipe. It dries in a few hours forming a new plastic pipe inside the damaged pipe.

As good as this sounds, the process is not foolproof. In fact, some contractors who do the work lack the confidence to provide a warranty. Problems develop when the epoxy does not adhere to the pipe wall properly, or when the coating is not evenly applied. Any subsequent leaks are more difficult to repair because no heat can be used. You may have no choice then but to repipe, which could have been done at the outset, and pay a second time to solve the same problem.

Pipe bursting, also called pipe splitting, is sometimes used to replace badly damaged water lines. It also is a trenchless solution, but instead of lining the inside of the damaged water line with epoxy, a new pipe is inserted with a “bursting head” that is a little bigger than the diameter of the damaged pipe. It destroys the old pipe as it is pushed or pulled through.