When it comes to the plumbing in your home, many people follow the maxim "out of sight, out of mind." As long as the faucets are flowing properly, you'll trust that the pipes behind the walls are in good condition.

Unfortunately, plumbing problems might only become apparent when they spring a leak. The Wall Street Journal recently reported that interior flooding issues are becoming more common, often as a result of older pipes and valves reaching the end of their lifespan.

Most types of plumbing will be reliable for several decades, but pipes will ultimately need to be replaced when they are no longer reliable. Keeping an eye out for problems can warn you about imminent trouble before it leads to catastrophe.

An annual inspection of any visible pipes, such as those that run through a basement or crawlspace, is a good habit to start. Joe Bousquin, writing for the home improvement site HouseLogic, says stains, dimples, or flaking all indicate that the pipe may be corroding. If you suspect that there might be an issue with the plumbing, schedule a visit from the plumber to inspect your water lines.

There are also a few warning signs that your plumbing isn't in good condition. Bell Brothers, an HVAC company in Mather, Calif., says the debris produced by corrosion in a pipe will inhibit the water flow. This will result in lower water pressure, which will be noticeable whenever you take a shower or use a sink.

Corrosion can also lead to water discoloration, particularly if you have galvanized pipes. Meticulous Plumbing Home Services, a company in Portland, Ore., says the water will usually take on a rusty, reddish-brown hue. Mark Carpenter Plumbing, a company in Clovis, N.M., says you may also notice that the water develops a more metallic taste.

Leaks can occur for a variety of reasons, but may be a result of your plumbing reaching its limit. Bell Brothers says that if a faucet is running slowly or your bathtub or toilet is slow to drain, you may have a leak somewhere in the system. Leaks can sometimes become apparent when water stains develop on a ceiling. Supply lines are more likely than drain lines to cause damage when they leak since they are pressurized.

It helps to know what kind of pipes you have in your home. This will give you an idea of when your plumbing may become troublesome, especially if you also know how old the home is or when the pipes were installed.

Most types of plumbing have a very long lifespan. Bousquin says brass, cast iron, and galvanized steel pipes will last about 80 to 100 years, while copper pipes typically last 70 to 80 years.

However, your plumbing may also start to show problems much earlier. Bell Brothers says galvanized steel pipes may only last 20 years, while the lifespan of brass and copper pipes might be as short as 40 or 50 years, respectively.

Galvanized steel pipes can be particularly concerning once they start to fail. These pipes are no longer used for residential construction, but were very popular between the 1930s and 1980s. Mark Carpenter Plumbing says these pipes use a zinc solution to coat the steel and prevent corrosion. As this coating starts to break down, the pipe itself will be more vulnerable to corrosion. The zinc coating may also have lead and cadmium in it due to the galvanizing process, and these metals can be released into your water supply as the coating erodes.

Some types of plumbing should always be replaced, even if they aren't near the end of their lifespan. Bousquin says lead pipes are long-lasting, but present serious health issues since the lead can leach into the water. Polybutylene pipes were used for a brief period from the 1970s to the 1990s, but should be replaced because they will become more brittle and likely to break.

If you suspect you might have lead pipes in your home, you can get a water test as confirmation. Meticulous Plumbing Home Services says you can also check an exposed pipe by scratching it with a screwdriver and placing a magnet on it. If the pipe scratches easily because the metal is soft, has a gray color, and won't hold the magnet, you may have lead pipes.

Replacing the plumbing in your home is the best option if you have aging pipes which are no longer reliable. Bell Brothers says the cost of this project will vary depending on factors such as the size of your home and how many fixtures need to be reconnected to new pipes.

This job can be completed over the course of a few different visits. Bousquin says you may want to start by only replacing exposed plumbing, which will be a more inexpensive endeavor. For pipes that are hidden behind walls, you might save up some money for the plumbing replacement or take on this work when the walls will be opened up for another renovation project.