Understanding the plumbing in your old house

By: Shannon Lee , Contributing Writer
In: Home Improvement Tips, Old House Construction

I know, I know…understanding the plumbing in your old house is just as likely as understanding the theory of relativity. But you have to start somewhere, right?

I've always thought one of the most interesting parts of old house renovation or restoration was figuring out what previous owners did with all those pipes in the walls. Sometimes it was very straightforward and had obviously been done recently by a professional contractor. But all too often, the pipes were in complete disarray, in a wide variety of types, and were routed in such a way that the plumbing shouldn't have worked at all -- but somehow it did.

Now that we are looking at upgrading the plumbing in our current home, I've again become interested in exactly what is what, where it goes, and what is best. Here's a brief rundown of what you need to know to start figuring out the theory of relativity…umm, I mean, your old house plumbing.

Old house plumbing materials

The good news is that most plumbing lines are designed to last a very long time, which is why some of the pipes in your house might have a lot of life left. But there are some pipes that will need to be replaced as soon as you can swing it.

Galvanized steel was popular before the 1960s, and it has wrecked havoc on old houses far and wide. These pipes corroded as they aged, and buildup in the pipes is quite common. If you have ever turned on the water in an old house and found ridiculously low water pressure when there shouldn't have been a problem, that's a clue to the presence of galvanized pipe.

Cast iron, hardy though it is, eventually does wear out. This is evident in the multitude of water line breaks cities and towns have to deal with on a regular basis. If the pipes leading away from your home are cast iron, be prepared to deal with their replacement sooner rather than later. It will happen!

There are other types of pipes that could cause problems, too. Lines leading away from your house might be plastic, which could get crushed over time by tree roots, or they might be made of clay, which eventually deteriorates. If you happen to have something called Orangeburg, you can't wait on changing the pipes -- this was made with tarpaper and is definitely on its way to failing if it hasn't already.

What it takes to fix old house plumbing

One of the first things you will need to do is replace the pipes where necessary. This is usually where you have older pipe that is falling apart, galvanized pipe, or joints between two different types of pipe that were joined without a dielectric coupling (as corrosion here is almost certain). The best options for replacement include copper, PVC, and PEX pipe. Copper is elegant but expensive, so tends to be used in areas where pipes are exposed. PEX pipe is great for colder areas, as it can withstand some freezing, and it's flexible for easier installation. PVC is cheap and serviceable, which is why it tends to be the standard.

Take this opportunity to install shut-off valves on all areas that need them, such as the pipes that feed the toilets and sinks. Many old houses require that water be shut off at the main, which is a true hassle, and might even be impossible if that switch is underneath a manhole in the street!

The remaining pipes should be inspected, especially those that connect to sewer lines. In some cases this might mean deploying a tiny camera to get a look at what is really going on in there -- this requires the help of a professional, of course. But once this is done, you will have a better idea of what long-term goals should be set for repairing the more expensive parts of the system.