The Building's Plumbing - Water, Waste and Gas System...

The water supply system is relatively simple in that one supply pipe comes into the home and is then split into the hot and cold water systems via the water heater. The primary source of your water can be from a city-wide public system or from a well on your private property.

To the right is a simple layout of a common hot and cold water supply system (To enlarge the layout, just click on the photo)-->>

Your supply water system has several key components.

  • First is the main water shut-off valve that is generally located on the outside of your home and is the first stop for all incoming supply water.

  • Next is the water meter (if you're on public water.)

  • After the meter is an inside shut-off valve. (The second chance to stop an internal flood.)

  • The water is then split into two uses - to the water heater for the hot side of the system and branched off to supply cold water where needed. In most cases, both hot and cold lines run near each other.

  • There is the water heater itself.

  • And last is the many-many branch shut-off valves. Typically one for every fixture and every source (hot and cold). Most fixtures, like a bathroom sink, will have two shut-off valves.

As I said before, aside from water leaks, there isn't much to a water supply system.

As you can see from the illustration to the left, the gas supply system is also a fairly simple system. Since our next chapter is on HVAC systems, I'll use a water heater to illustrated the gas piping system key components.

Although there are several types of burning fuels used in a home, we'll only deal with the most common, which is natural gas, generally supplied by a utility company city-wide. 

Natural gas comes into the home and is first stopped at the outside gas meter. The gas meter keeps count of gas consumption and it is then piped (usually black iron) into the home to a second shut-off valve. Once inside the home is then split or branched as needed for various uses.

Most homes using gas have a gas furnace and gas water heater, but can also have several other appliances which require the use of gas.

 The gas system is the only home system with double shut-off valves. One at the branch source and one at the supplied component. This is for safety and allows you (or a fireman) to get to a source to cut off the fuel supply feeding a fire.

From the above information, you should have a small understanding of how all of the major plumbing systems in a home work. When your Home Inspector is inspecting you home, feel free to ask questions. I only remind you that the only dumb question is usually the one no one asked. Remember that a good inspector should also be a good teacher and part of his/her responsibility is to educate the home buyer/seller/investor.