While the exact cause is uncertain, it is believed that the oxidants (such as chlorine) in public water systems react with the plastic, causing it to flake and become brittle. As the integrity of the piping deteriorates, tiny fractures develop, which can expand over time and cause a sudden failure of the pipe and resulting water damage. Galvanized steel is another type of pipe material that is no longer installed for water supply piping, although still available and used for repairs of existing systems. It was often used for water supply piping in homes until the early 1970s, but not used today because corrosion problems limit it’s useful lifespan to between 40 and, at best, 50 years. Rust-corrosion accumulates inside the pipe and causes a plumbing version of arteriosclerosis, with the gradual hardening-of-the-arteries narrowing the diameter of the pipe in horizontal runs to the size of a soda-straw in places. Essentially, it rusts from the inside out. This restricts the flow of water to faucets and showers and, eventually, the corrosion causes the pipe to spring leaks--usually the first place being in the ground under the home’s concrete floor slab, or near the water heater due to an electrolytic reaction to copper fittings speeding up the corrosion. The photo below shows the end of an abandoned section of galvanized pipe in a laundry room wall, where it was cut-off at the juncture with a washing machine faucet. As you can see, the water flow was severely reduced from the buildup of rusty crud in the pipe. Surrounding it is the cream-color plastic pipe that replaced it, called CPVC. Both PB and galvanized pipe may be problematic when you apply for homeowner’s insurance for an older home. Some companies will not write a policy for homes with PB or galvanized, and others require a licensed plumber to certify that the pipe system is in satisfactory condition.2) Pipe material and fixtures that are at the end of their serviceable lifespan - Every component of a home has an average lifespan. Sometimes it will last longer than the average and, then again, occasionally it fails sooner. Here’s some plumbing life expectancies: WATER SUPPLY PIPING Copper - 60 to 80 years Galvanized Steel - 40 to 50 years CPVC and PVC - 40 to 50 years PEX - 40 years DRAIN PIPING Cast Iron - 50 to 65 years Galvanized Steel - 40 to 60 years Copper - 60 to 80 years PVC - 50 to 70 years PLUMBING FIXTURES Water Heaters - 10 to 20 years Faucets - 15 to 25 years Sinks, Tubs, Toilets - 40 to 80 years Shut-off Valves - 20 years Advanced deterioration of plumbing is easy to spot. The photo at the top of this blog is old galvanized steel pipe that is clearly showing its age, with heavy corrosion and beginning to leak. In other instances, the piping or fixture may look younger that its known age; but, as plumbing approaches the the end of it’s estimated lifespan, you should expect replacement soon. Water shut-off valves have a rating of 20 years because they tend to be frozen in the open position at that age. Your home inspector will note any plumbing that is visibly deteriorated, but inspectors do not test shut-off valves.3) Defective repairs made by the homeowner or a handyman - Just because a professional plumber did not do all the plumbing work in a home does not automatically mean that it is bad. However, we practically never see incorrect plumbing installation by a licensed plumber. Sink drain configurations that would make even Rube Goldberg laugh occasionally happen when a non-professional tackles a home renovation project. Traps installed backwards or doubled-up, poorly secured pipes, unvented drains, and unsafe water heaters are common. To read more about water heater installation, see our blog “What are the most common installation problems with water heater replacement.” Also, accordion-type piping is a sure sign of amateur plumbing work. The photo below shows a homeowner’s sink drain repair using accordion pipe as a tailpiece, connected to three P-traps in a configuration that is absolutely guaranteed to clog. Although home improvement and hardware stores sell the stuff and it makes easy work of connecting two pipes that are not aligned, the pipe is not rated for installation by any plumbing codes and the ridges collect hair and debris. Here again, your home inspector can help you sort through any haphazard plumbing repairs and determine what needs to be redone. Because the age and condition of an older home’s plumbing components do not always correspond with the age of the house or a date of renovation, a careful evaluation of the system is always a sensible part of the due diligence necessary in buying a home.