In a previous piece I wrote for this site, I said that the buyer should beware when buying a house, and especially so when the house is old. This is, as I’ve said before, because older homes were built to meet the standards and rules of a different time, and those standards may not equal the usual specifications and demands of homes today. Though most pipes can perform well for decades at a time, not replacing them when its time can put you in hot water.
There are two types of household pipes: supply pipes, and drain lines. Supply pipes bring water into your home and throughout it, the drain lines use gravity to take waste and water out of your home and into a sewer or septic tank. Drain lines are your responsibility on your property, but past the street they are not your concern.
Drain lines in newer Canadian homes are typically made from cast iron or acrylonitrile-butadiene-styrene (ABS), a rigid plastic material. Older homes also often use cast iron for their drain lines, but most of them (supposing someone hasn’t recently replaced them) will have clay, or tarpaper pipes. Cast iron is good for drain lines because it lasts for up to 100 years, but when they are around this age they are vulnerable to corrosion. Clay and tarpaper pipes are no good, because they crack or tear and are susceptible to being crushed and having roots intrude. If this happens, then your household’s flow of waste to the sewer can get backed up and leave you in a mess of a situation. Replacing old pipes is usually a good idea, but if you find either of these drain line materials going to your sewer, you should not hesitate to call a professional plumber to replace them. ABS, or another kind of rigid plastic pipe (like Polyvinyl Chloride, PVC) would make an ideal replacement for a drain line: they are resistant to corrosion (as drain pipes do not carry hot water), and they are relatively cheap and easy to install. Some plastic pipes corrode when carrying very hot water, but drain lines never do.
More likely to fail than drain lines are supply pipes, as they are under a lot more pressure bringing water into the home constantly, some of it being very hot water. These need more attention and are more likely to leak. Commonly used in-house piping includes, but is not limited to, polybutylene, brass, copper, galvanized steel, and lead.
Polybutylene is a flexible plastic material, commonly used in piping between the late 70s and early 90s. It has been installed in hundreds of thousands of houses in Canada. Many plumbing and home renovation websites (mostly American made ones) will warn you against using this material for its likelihood of flaking on the inside (caused by heavily chlorinated water) and because of how often it breaks. For the Ontarians reading this, have no fear, for our water is far less chlorinated than most American water is, so your polybutylene pipes will not flake. Most insurance companies in Canada do not consider it to be an added risk factor. However, as I said before, plastic pipes aren’t the best for dealing with hot water. Polybutylene is permeable to oxygen, making it oxidize hot water, which can be straining to your water heater. You should make sure this kind of pipe is not connected to your water heater. If the chlorine levels are high where you live you should install different pipes or place a filter on the water’s entrance to your home.
Most people are already aware of how bad lead can be, but lead pipes aren’t inherently an issue. Lead pipes can last for up to 100 years, but when they age past this you need to replace them. If you have reason to think you have lead pipes in your home, have your water tested for lead. If the lead content shown is 15 parts per gallon or higher you need to replace them. Call a professional.
Pipe Types and Longevity:
Drain Lines and Life Expectancy
Clay – 50 years (could be far less if close to roots)
Tarpaper (coal tar-impregnated wood fibre) – ~35 years
Cast Iron – 100 years
ABS or PVC (rigid plastics) – 100 + years (indefinitely, in the right conditions)
Polybutylene (flexible plastic) – 10-15 years
Brass – ~50-60 years
Copper – 50 + years
Galvanized Steel – 20 + years
Lead – 100 years