In this article, excerpted from his book Build It Right: What to Look for in Your New Home, Myron Ferguson talks about the different types of plumbing used in new home construction and some of the potential problems that you should be aware of.

For many decades water pipe was made of iron-with its rust problems and limited life. Leaks in walls of older houses were commonplace. Then came copper pipe which, while more expensive, offered such great advantages that iron pipe became a thing of the past. Today we have several types of plastic pipe that are less expensive and potentially longer lasting than copper.

In this article we look at these different types of water pipes, their pros and cons, and at the two different kinds of drain pipes. Taps and faucets are generally a matter of personal preference and cost except for exterior hose bibbs where a common arrangement is anything but user-friendly.

Plumbing plans are fairly simple and straightforward unless you want something unusual like circulating hot water. There's no excuse for a layout that brings you a sudden change in shower water temperature when someone washes their hands or flushes a toilet. If you can check this in the model house, it's a good idea. You should also check that outside hose bibbs are convenient and not located where growing plants will make them hard to get to.

Types of Water Pipe

While copper has been the most commonly used pipe inside new houses, several types of plastics are becoming more popular. There has been a reluctance by the plumbing industry to make the change but now three types of plastic pipes have been approved by several building code groups, most notably the Council of American Building Officials (CABO) whose codes are the basis for many state codes. Note, however, that a few states are slow to agree to let plastic piping be used in homes. But this is changing. You'll need to check your own state codes.

The main argument against plastic pipes is that they haven't been in use long enough to ensure that they won't cause trouble in the future -- the old chicken-and-egg riddle. And, in fact, there was a serious problem with polybutylene (PB) connectors that resulted in numerous lawsuits because of damage that was done to homes by leaky PB joints. There is a consensus that these problems have been solved. Cross-linked polyethylene has been available for many years but the reluctance to use it has held back its more widespread acceptance. This is changing.

Copper

Copper is the material of choice by most plumbing subcontractors even though installing copper pipe takes more skill than plastic. Copper isn't without its problems, however. In southern California there have been reports of pin hole leaks in copper pipe presumably due to chemicals in the water. California is now starting to allow plastic piping inside residences.

Chlorinated Polyvinyl Chloride (CPVC)

CPVC is similar to PVC, the white plastic pipe used in lawn irrigation systems. Unlike PVC, CPVC doesn't soften when used for hot water. CPVC is 15 to 25 percent less expensive than copper. The installation times for CPVC and PVC are similar when done by an experienced installer.

Polybutylene (PB) and Cross-Linked Polyethylene (PEX)

Polybutylene and cross-linked polyethylene pipes are similar in that they are flexible plastics, they come in rolls, and require special fittings that are neither soldered nor cemented but are mechanical in nature. These fittings must be approved by local building officials.

The flexibility of polybutylene and cross-linked polyethylene tubes and pipes makes it possible to use them in a different way that has definite advantages, both during installation and later when in use in the home. The main water line coming into the house feeds a manifold with multiple outputs. Each output connects to an uncut piece of pipe that goes to a single outlet: a faucet, dishwasher, toilet, tub, shower, or washing machine. Joints, elbows, and couplings are not needed.

This results in lower installation times than needed for copper and a lower cost both in material and labor. Special tools and skills are needed for installation. (WIRSBO, a manufacturer of PEX, offers a twenty- five year warranty if the installation is done by a trained plumber, one year if you do it yourself.)

Because there is only one faucet per line coming from the manifold, turning on a second faucet has little impact on the flow to one already running. Thus, if you are taking a shower and someone turns on a faucet someplace else, there will be very little impact on either the amount or the temperature of your shower water.

Both PB and PEX are approved for hot as well as cold water.

Water Heaters

Be sure the water heater is suitable for your family. The tendency for builders is to use the smallest (and least expensive) heater allowed by code.When you want hot water quickly you have two options: re-circulating hot water or an auxiliary hot water tank.

Re-circulating Hot Water

You are already acquainted with re-circulating hot water-or did you ever wonder how you got the hot water so fast in your hotel room? The process involves doubling the amount of hot water pipe in the house. One pipe carries hot water from the heater to the faucets and the other carries the unused water back to the heater. A small pump keeps hot water circulating through the system. Both directions of pipe must be insulated if they are copper. The plastic in PB and PEX offers a certain amount of insulation in itself and additional may not be needed. WIRSBO says it's not necessary with their PEX. Check with the manufacturer of your piping and with your local building officials if you consider re-circulating hot water.

There's an initial cost for putting the system into place and an ongoing cost for the electricity to run it. Both costs are small, particularly when you put a timer on the system so that it doesn't run while you sleep.

You make up at least a part of the ongoing cost since you no longer have to waste water by running it until it gets hot. If your builder will consider having it installed, find out how much it will cost and you decide if it's worthwhile for you. PB and PEX piping are attractive in re-circulating hot water systems because they are easy to install, they don't have the potential noise problems of copper and the plastic pipe itself acts as an insulator.

Auxiliary Hot Water

Small heaters that mount under a vanity counter can provide hot water immediately. If you want one for a shower or tub, the heater will need to be bigger than one that furnishes water to the basins only. As with other hot water heaters, you'll need gas or electricity brought to the heater's location. The feasibility of doing this and the cost will depend on how big the heater is and on the impact it may have on the rest of the house design.

Water Pipes in Outside Walls

A good house design will minimize runs of water pipe in the outside walls because of the danger of freezing although for kitchen and vanity sinks short runs of pipe are often located there.

Outside walls in today's new houses are usually well-insulated. When water pipes are run in these walls, it is important that the pipes be kept toward the inside of the walls rather than the outside. Also, the wall insulation must be installed so that most of it is between the pipes and the outside wall and little or none is between the pipes and the inside wall. Plumbers and insulation installers understand this and normally install it this way. However, it doesn't hurt to check.

Nail Plates

Pipes running through studs or plates are always in danger of being punctured by wallboard fasteners-nails or screws that are 1 1/4- to 1 5/8-inches long and are driven into studs behind the wallboard. When the wallboard goes up, the installer can't see where the pipes are. Plumbers are supposed to put pieces of galvanized sheet metal, called "nail plates" or "safety plates", on the outside of the stud or plate to prevent the wallboard installer from putting a nail or screw there and inadvertently punching a hole in the pipe. The builder or his construction supervisor should check that nail plates are in place properly before the wallboard is installed, but they are sometimes missed.

Besides the obvious problem when an immediate leak occurs, improperly placed or missing nail plates can result in subtle problems that may not be seen for several years. Small leaks in drain lines are not always self evident and the dampness may be contained inside walls where it can rot the wood without being seen. There is also the possibility that a wallboard screw will penetrate a water or drain pipe but the screw itself plugs the hole until it rusts out a few years later. If you can, double check that nail plates are in place to protect all pipes before the wallboard is installed. The builder's warranty for things like this lasts only one or two years.

Noisy Pipes

You can reduce water and drain pipe noise by paying attention to how the pipes are installed. As an experiment when you visit model homes, have your spouse turn on a faucet in one end of the house and see if you can hear the running water in the other. Some houses are significantly better than others in this respect.

Water running through a pipe is noisier when the pipe touches wood because the wood can act as a sounding board. Pipes should be kept away from joists and studs. Plastic piping used in water distribution systems has additional advantages here. First, most noise originates where the direction of flow changes abruptly and this doesn't happen with plastic in normal installations. And, copper will carry noise along the pipe more readily than will plastic.

Drain water falling from the second floor of a house makes noticeably more noise in plastic than in iron pipes. If iron pipes are wrapped with insulation, the noise from the second-floor drain pipes will be just about eliminated. However, iron pipe rusts, so check its expected life in your area before having it installed. For either iron or plastic, wrapping with fiberglass insulation will help deaden the noise.

Hose Bibbs

You'll want hose bibbs on the outside of your house. Most builders put in two: one in front and one in back. For most of us this isn't enough. If you have an RV pad, you should have a hose bibb there. In any case, an additional hose bibb on at least one side of the house is useful.

If you need hot water to wash your car, have a bibb installed in the garage, connected to both hot and cold water. Be sure you take a hard look at the type of faucet that is used. The common faucet used for mixing hot and cold water restricts the amount of water that can be passed. This is no good when a high volume of water at full pressure is needed.

Make it known, either in writing or on a drawing, where you want the hose bibbs. Allow the plumber some freedom to minimize the cost of putting them in place, but be sure your wants are known.

In areas where there is danger of water freezing in hose bibbs, plumbing codes require a means of draining the water from the bibbs in the winter. Two methods are permitted in the codes: a regular hose bibb with a stop-and-waste valve or a frost-proof hose bibb.

Stop-and-Waste Valves

Stop-and-waste valves are installed in an accessible heated location where there is no danger of freezing. The "stop" part is simply a turn-off valve. The "waste" part is a plug on the valve which can be removed to allow water to drain.

he hose bibb is connected to the stop-and-waste valve with pipe that may be exposed to freezing conditions. In the autumn the home user must:

1.0 Turn off the water at the stop-and-waste valve.

2.0 Open the hose bibb and take care of any hoses which may be connected.

3.0 If the bibb and pipe don't drain by themselves, the waste plug must be removed to let the water out.

In the spring the above process must be reversed.

Unfortunately, not all plumbers follow the code carefully and not all inspectors see that they do. In far too many cases the stop-and-waste valve is placed where it is not readily accessible, making it virtually useless. If your builder or plumber insists that frost-proof hose bibbs are not a good idea, then you should insist that he put the stop-and-waste valves where you can get to them easily and that pipes drain by simply opening the bibb.

Frost-Proof Hose Bibbs

The frost-proof bibb includes a piece of copper pipe as a part of the bibb itself. This pipe extends the valve part of the bibb back into a part of the house that is heated and where there is no danger of freezing. When it is turned off, water drains from the exposed part of the hose bibb and no damage occurs.

There is a precaution, however. Sometimes hoses with closed nozzles are left connected so that the water cannot drain. This has happened often enough that plumbers in some localities have an aversion to using these bibbs at all. Properly used, they effectively eliminate problems with freezing.