Every day you have choices: hamburger or hot dog, apple or orange. However, millions of homes in the United States were built before there was a choice in water-supply piping materials. And if you happen to own one of those homes, you will be faced with the problem of replacing that only option - galvanized steel pipe. While replacing pipes may not be on your top-10 list of things to do, it will become very important when it takes an hour or more just to fill up the bathtub. Galvanized steel pipes do not care whether they are delivering hot or cold water; sooner or later they will plug up. Uncoated steel pipe was used for water piping as early as 1850.

Since the early 1930s, the commonly used material has been galvanized steel pipe. Galvanized pipe has a problem: As water flows through the pipe day after day and year after year, minerals that occur naturally in the water cling to the zinc-coated interior walls. As time goes on, the inside diameter of the pipe will eventually start to close up. After years of mineral accumulation, the water will flow at a very low rate or, even worse, stop altogether. It is also very common for galvanized pipes to leak at the joints, because the threads are the thinnest part of the pipe. Corrosion will often start there and develop into a leak as the zinc coating wears off and the steel pipe beneath starts to rust. That is another reason why every year thousands of homeowners replace the water piping in their home.

Not all water pipes are replaced because they are old; sometimes newer pipe can cause problems, too. In the early 1970s, polybutylene (PB) tubing became an instant hit with many contractors because of its fast and easy installation and economical price. By the late 1980s, over 6 million homes had installed it as their water-supply piping. Everything seemed to be working flawlessly; this wonderful new product had revolutionized the plumbing industry. Several years later, things began to change. PB tubing or fittings would fail without any warning and start to leak. One theory is that chlorine in the water reacted adversely to the resin in the tubing and fittings, causing them to become brittle and crack or split, but the exact cause has never been agreed upon. However, a multi-million-dollar class-action lawsuit was filed against the manufacturers of the resin used in PB pipe.

After extensive litigation, the manufacturers were ordered to deposit a minimum of $195 million in a fund to replace PB plumbing and repair homes that suffered water damage. The settlement required that the PB plumbing must have been installed within a certain time frame, and the house must have had at least one leak. See www.pbpipe.com for more details on whether your installation qualifies. Today there are better piping choices that should last as long as your home. Both the International Plumbing Code and the Uniform Plumbing Code list more than 15 different types of material that are approved for use as water piping in your home. Of those 15, only three are practical choices for use in today's homes. Some of the less practical include brass pipe, which is very expensive and labor-intensive to install. Five different types of steel and iron pipes are approved, but they would have the same problems as galvanized steel with rust and corrosion.

ABS (acrylonitrile butadiene styrene) and PVC (polyvinyl chloride) plastic pipe are not approved for hot-water distribution. Polyethylene (PE) is approved, but is mainly for underground lawn-sprinkler and utility water lines in exterior applications. The remaining types of pipes are not practical because they are not manufactured in sizes that work in household applications. That leaves the three practical choices of copper, chlorinated polyvinyl chloride (CPVC) or cross-linked polyethylene (pex). If you hire a plumbing contractor to do the job, he or she will discuss with you the type of pipe they prefer. However, if you are not familiar with or are not comfortable using that pipe in your home, check with other contractors and get other ideas for the job. Copper Copper water pipe comes in three wall thicknesses.

Type M is the most commonly used, and Type L has a thicker wall and can also be used in residential piping. Some plumbing codes require that underground copper pipe be Type L, and it is also frequently used in commercial and industrial applications. The last type of copper water pipe is Type K, which has the thickest wall. Type K is used for underground water service to carry the water from the well or water main into your house, and while it can be used inside the home, it normally isn't. All pipe used for water has to be marked in some way to identify the type: Copper Type M is marked with red printing, Type L with blue and Type K with green. The identification must also be imprinted or incised into the pipe. For many years, copper water pipe and fittings were joined together using 50/50 solder (50 percent lead and 50 percent tin). This type of solder was discovered to be a health risk because the lead would leach into the water and possibly cause serious health problems. Lead was banned from use in plumbing solder in 1986, and new solders were developed that work just as well. Many of the new solders contain a small percentage of silver, and these joints are stronger than joints with 50/50 solder.

Copper pipe is still used very widely and is available in 10- or 20-foot lengths. New methods of connecting copper pipe and fittings eliminate the need for torches and the accompanying hazards of fire. Copper pipe can be joined by using an electric crimping tool that crimps a specially made copper fitting onto the pipe, with an O-ring in the joint to make it watertight. The system is called ProPress and makes the installation of copper pipe much safer and faster with no heat, flames, flux or solder. In certain areas of the country, the pH of the water can be a factor if you choose copper pipe. Copper works very well in water conditions that have a pH as close to seven as possible (neither acidic nor alkaline). If your water tests significantly lower than seven, copper may not be the choice for you. However, copper is certified from a health-effects standpoint - in accordance with National Sanitation Foundation Standard 61 - for use in potable waters with a pH above 6.5. Below this level and without water treatment to inhibit corrosion, copper may leach into the drinking water.

CPVC This thermoplastic pipe has become a popular alternative to copper because of its ability to resist acidic and aggressive water conditions, as well as the effects of chlorine and other chemicals. CPVC has been used for water-supply piping for over 35 years in the United States with no serious problems reported. All potable-water piping is tested and certified by either Underwriters Laboratories or by the NSF using standards set by the American National Standards Institute. All potable-water piping must now be certified lead-free by NSF Standard 61 and should bear the stamp "NSF - PW. Like copper, CPVC pipe is sized from the source of the water supply, whether it is the water meter, well, or water heater. The largest section of pipe is located closest to the source; this is the section of pipe that will carry the largest amount of water to the rest of the supply system. As additional pipe is installed to fixtures throughout the house, the amount of water needed drops - as does the pipe size - until the smallest pipe feeds the last couple of fixtures in the system. CPVC pipe and fittings are put together by means of a solvent weld. They actually melt into one solid piece with the help of solvent weld cement. The process takes about 24 hours to cure fully. Water should be turned off until the cure time has been completed, then the pipe and fitting are ready for full water pressure.

The CPVC pipe and fittings have become very popular with the do-it-yourself homeowner because it is very easy to work with and install. The pipe is available in 10- and 20-foot lengths and can easily be cut with a hacksaw. Because there is no soldering, installation is much easier than copper for the homeowner. CPVC is available in the same sizes as copper and galvanized steel. Pex Cross-linked polyethylene tubing was invented in 1968 and is the most recent addition to the water-piping market. Pexhas been used in Europe for household water supply since 1973, where it has proven trouble-free. Unlike metal pipes, pex is resistant to problems associated with poor water quality. Pex technology was brought to the United States in 1985 and gained popularity in the late 1990s. Today, many companies manufacture pex in this country. Its natural color is cloudy gray; however, some manufacturers color-code their tube with red for hot and blue for cold, making identification easy within the home. The tubing is extremely flexible and easy to work with, unlike copper or CPVC, which comes in rigid lengths.

Pex comes in a roll like garden hose and weighs four times less than copper. Because pex is manufactured with a thermal memory, if the tubing becomes kinked during installation, the installer can heat it with a propane torch until it turns clear as glass, without burning it, and as the tubing cools, it will return to its original shape. A very popular feature of pex is the method of installation. Typically, two manifolds (one for hot water and one for cold) are mounted on a wall and the water service is then connected to them. The manifold is basically a piece of pipe with a number of valves mounted on it. A piece of pex is connected to each valve and runs to a plumbing fixture somewhere in the home. The manifold system gives the homeowner the ability to turn off the water to any plumbing fixture in the house without affecting supply to any other fixture. Installing pex does require special tools, and the pipe and fittings should always be the same brand.

Certain brands of pex tube may not be compatible with different brands of fittings and could cause a leak if mismatched. Additional Information All three materials considered will do a good job. Whether you decide to do the work yourself or hire a contractor, be sure to look at all the different types of piping and understand how they are installed. Installation instructions can often be obtained from the pipe manufacturer and should list any special tools needed for proper installation of the pipe. The price of copper varies with the metal market. Many contractors will buy a large amount of copper pipe when the price is low. CPVC and pex do not vary except in normal price changes due to manufacturing costs. When you look at the cost of the actual pipe itself, CPVC is the lowest, followed by pex and then copper on the higher end. However, fittings are different. CPVC is the least expensive, followed by copper, and then pex. Labor costs can be a large part of a new piping estimate. Copper and CPVC have similar installation times, but pex is quicker to install because it requires fewer connections and fittings.

Keep in mind that pex installations use more pipe, which can eat up some labor savings. The cost of repiping a home depends on the size of the house and the amount of pipe needed. The homeowner with an average-size home can expect to pay anywhere from $2,500 to $7,500 for a contractor to complete the job. After new pipe is installed, many homeowners like to insulate their copper and CPVC water pipes to keep the heat within hot-water pipes and prevent condensation from dripping off cold-water pipes. Pipe insulation can be made of fiberglass or foam. Your local plumbing or building inspector can be a great source of information for what materials are permitted under local codes and what pipe performs well in your area. Also remember that in most jurisdictions, whether you do the work yourself or hire a contractor, your local department of inspections will probably require a permit for the work. When the work is completed, an inspection will be required to make sure the work meets the corresponding codes. Most inspection departments require at least a 24-hour notice that a job is ready for inspection.

Plumbing codes require certain types of pipe to be installed in specific ways; be sure you are familiar with the code in your area before you start installing pipe. Your local home center or plumbing-contractor showroom can be useful for looking at the materials needed to do the job. Arthur Thompson is a freelance writer from New Brighton, Minn. He has been a master plumber for 24 years and holds certifications as both plumbing inspector and building official.