Supply side plumbing is the water that brings potable water into the building. Copper used to be the standard material used to do this, however, PEX, or cross-linked polyethylene, is rapidly replacing copper as the predominant material given its comparable performance to copper, but at a fraction of the cost for material and a fraction of the time required to install. CPVC can also be used, but is not as common as copper or PEX.
Main Supply and Meter
For buildings using a central water source, there should be a water meter at the inlet line. This is very useful in detecting supply side leaks. There should be a shut-off valve at the meter. This is the main shut-off and will interrupt the supply of all water to the building. Though not required, there should be a hose bib or bleeder valve at the meter as well. This makes it easy to drain the supply lines when winterizing the building.
Hot/Cold Split
From there, the water is generally split with a “tee”, with one line supplying the building with cold water, and the other side feeding the hot water heater (HWH). In most cases, the HWH is located in the basement or a utility room, however, there are also point-of-use water heaters that heat the water where it is used. In these cases, only cold water is distributed throughout the house, with the water line split at the point-of-use to feed a HWH.
Using PEX, it is easy to identify hot and cold water lines. Hot water lines are red, and cold are blue. There is no difference between the colors in terms of performance, but are just used for identification. Using color coded pipe properly avoids mistakes that are more common than they should be when using copper. Two common mistakes are reversing hot and cold faucet handles, and supplying a toilet with hot water!
When the water lines reach a fixture that uses both hot and cold supply, the hot supply should be on the left, and the cold supply should be on the right.
Access and Shut-offs
At each point where the hot and cold water are branched off to serve a new room, there should be a shut-off at an accessible location. Shut-offs should be located in basements where the plumbing is exposed, or behind an access panel. Shut-offs make it easy to isolate sections of plumbing which makes finding a supply-side leak easier and localizes affected areas during repairs or upgrades.
It is a good idea to find all the shutoffs in the house before there is a problem. That way, in case of emergency, the supply of water can be cut off quickly, limiting the damage done to the property.
External Hose Bibs
Hose bibs are generally located outside the house, and sometimes in the basement. Hose bibs are supplied with cold water only. It is important to winterize hose bibs in the winter so that the pipe supplying it does not freeze and break. This can be done by shutting off the supply at the shut-off and draining the water out of the line.