Understanding Plumbing Terms

Plumbing seems to be the most misunderstood of all operational installations in a home judging by the number of questions we get at inspections.

Depending on whether you live in the city or country, you have either a well pump or a water meter. The first thing every homeowner should know is where the main shut-off is. The vast majority of homes have individual shutoffs on their toilets and, when you have a leak at a sink or tub, you need to get to this shut-off valve quickly. If you have had a home inspection done, the location should be on your report.

Home plumbing is not complex, but I am going to break my answer into twO parts, starting with your home water supply.  This supply arrives as cold water and is then branched off to your hot water heater. The majority of homes, built after WW2, had some galvanized or most likely copper supply lines and copper is still used today. Some builders swear by copper for supply water lines and with its track record it’s hard to argue. The largest drawback today is its price; the new plastic pipes are considerably cheaper and, unless you have got the “knack” of soldering like a pro, then the new PEX pipe is worth trying.

In the early 80’s we saw the beginning of plastic pipe for water supply and its early years had some “bumps” with respect to quality and long-term use. One early plastic pipe called Polybutylene or “Poly-B” collected its share of problems and resulted in some large lawsuits. The issues with this light grey colored plastic pipe were mostly related to the method of installation. However poor plastic connectors that developed leaks and any high flow rate or excessive chlorine content are known to cause this pipe to deteriorate and leak. By 1988, this plastic pipe was gone and replaced by Chlorinated Poly Vinyl Chloride or CPVC, as it is known. This plastic pipe, which is usually a milky white color, has been used, successfully. However, it did have some early joint issues. It is also rigid and requires ample hangers to support it. In the late 80’s, plastic tubing called cross linked polyethylene or PEX was introduced. Unlike CPVC or PVC this pipe comes in rolls, can turn a 90-degree corner and has a simple, yet very effective, connection banding system. From a personal perspective, the plastic pipe industry now has a real competitor to copper pipe. Today PEX comes in colors, blue for cold water and red for hot, along with the regular white PEX. There are actually two kinds of PEX; the standard water supply PEX and one that does not allow oxygen penetration. This is used in radiant floor heating and some installations in the food industry.  We rarely see a new home plumbed in copper water supply pipe any more.

Now that we know the different kinds of water supply pipe, let’s look at the other specialty fittings. When connecting to a sink or toilet the majority of plumbers today use a braided steel or plastic flex line. This allows them some tolerances for the dozens of different taps and fixtures on the market today. If you are having any taps replaced and have copper connected to the taps, this is now the opportunity to add a small shutoff called a stop valve. One of the areas where a large number of leaks occur is where you make the switch from one kind of supply pipe to another. This is called a transition fitting and there are numerous kinds. In older homes, the point where galvanized pipe and copper supply pipe are connected is a known area of corrosion or galvanic reaction. A connector called a “dielectric connector” is used. While I have heard of successful use of these fittings, I have also seen them used ineffectively. To ensure you have the correct fitting, when you to from one material to another at a joint, pay close attention.

Two areas of frustration in a home, generally with copper pipe is sweating and hammering. If you are convinced that the drips from your pipe are sweating and not a leak, then foam pipe insulation will usually correct this problem.  Hammering is caused by poorly secured pipe; sometimes a hot water line is the culprit as they expand slightly.  A vibration can occur in the lines as valves or taps are opened and closed. Often times it is accentuated if you shut the tap off quickly. Over an extended period of time, this can cause damage to connections and leakage can result. The solution is actually simple, though access to the pipes may not be. If you can access the suspect pipe, you can add a length of pipe at least 12 inches long above the fixture. This is known as an air chamber and will cushion the momentum of the water, which is causing the problem. One common area of hammering is a shower, and this is often happening where the bracket the plumber has driven into the framework has either failed or the solder joint supporting the pipe has broken. This “bracket” is sometimes a length of copper pipe with the ends flattened and then driven into the wood studs, but there are better methods.