A home’s plumbing consists of the incoming water supply, water supply lines, fixtures, and waste drain lines. We assume that the water service and the sewer service are run and maintained by the local municipal jurisdiction in Michigan, and we refer to these systems and public systems. Water heaters, kitchen appliances, and well and septic systems are covered in different blogs.
The incoming water line enters the home through the basement floor and we call this the service line. It is usually ¾” copper. Homes built in the 1910s & 1920s sometimes have lead service lines, this subject will be addressed in another blog. Some homes have plastic service lines, and some older larger homes have services sized to 2”. The service line will have a shut-off valve, a meter, and another shut off after it enters the house. The dividing line between you and the local system is the valve downstream from the meter. The municipality owns the meter, the service line and the shut-off valve upstream from the meter. Most municipalities read the water meters from a remote sensor on the outside of the house, others use a satellite communication system that eliminates the need for meter readers.
The water is distributed throughout the house to the water heater and the plumbing fixtures by water supply pipes. These pipes are usually ¾” & ½” copper pipes. Some older homes have galvanized steel supply pipes. These pipes, especially the hot water pipes, are prone to clogging, just like arteries. Some newer homes have PEX or CPVC supply lines. These pipes are easier to install and have much less residual value.
The house has plumbing fixtures to process the water. At a minimum, there is a sink, toilet, and bathtub shower. They have water supply pipes feeding them and drain pipes to take away the waste. Water is considered to be potable until it enters the fixture vessel where it becomes waste. A house may have a stall shower, stand-alone tub, whirlpool tub, bubbler tub, bidet, etc.
The waste is collected by drain pipes that drain the waste down drain stacks. These drain stacks have vent pipes on them that extend through the roof. In order for water to drain efficiently down, air must go up. These pipes are usually cast iron and PVC, the early 60s had copper drain lines. The stacks drain through the basement floor, meet up and drain to the main municipal sewer line. The homeowner owns the drain line all the way to the main sewer line. Note the difference between the water service line. These pipes are usually clay crock, newer homes have PVC, a few had Orangeburg tile which will be covered in another blog.
What does a home inspector look for in a plumbing system? We look at the service pipes, the distribution system, the fixtures, and the drain pipes. We run water at all thfe fixtures. We comment on any leaks, present or past. We comment on pipe, valve and fixture defects. Limitations include plumbing lines behind finished surfaces, shower pans and water lines below ground.