Residential Plumbing Systems

Generally there are two basic types of residential plumbing or piping systems layouts found in typical residential piping; series plumbed and branched. There are of course, many variations and  combinations of the two types. 

The figure below represents a typical series plumbed system. I have simplified the illustrations showing only the water heater and sink type fixtures, leaving out showers, bath tubs, etc.

A series plumbed system means that the water lines go from one fixture to the next, then from that fixture to the next, etc.

Branched plumbing systems are far more common.

The fixtures are shown in the blue prints, but how the piping gets to and from the fixtures is not shown. Normally, it's left up to the plumber to figure out the best way to plumb the house. Often this results in less than optimum plumbing layouts.

Even with identical floor plans there can be a number of variations in how the piping is laid out from one house to the next with residential plumbing.

The above diagram shows a branched residential piping system. This is not an efficient way to plumb residential systems.

The above diagram shows another residential plumbing system, a branched system where all of the fixtures at least have some common piping. It's a better green plumbing layout, but not perfect.

Cold water pipes are not an issue, since there is no need to purge water from the cold side of the plumbing. Hot water pipes are another matter. Since you often need to purge the cooled off hot water out of the pipes before you can get hot water.

Often due to the hot water pipes being in a crawl space, behind walls, and in attics, it is easier to determine what kind of system you have through testing. 

This can be done by measuring how long it takes to get hot water at each fixture allowing the hot water to cool between measurements. 

Then run the furthest fixture from the heater  until hot water arrives at the fixture, and then immediately test the other fixtures to see if hot water reaches the fixture more quickly than normal.