Planning home plumbing diagrams

Planning home plumbing diagrams for smaller homes is important because a good plan will maximize energy efficiency. When you use plastic tubing for fresh water, each line is dedicated to its own fixture so you don’t need to put a tee in the line anywhere. You'll have a hot and a cold line from the Pex manifold.

Here is the plumbing diagram for a Pex hot and cold water system. The main water line will branch off with one line going to the cold side of the manifold and the other line going to the water heater. That hot line will then leave the water heater and go back to the manifold on the hot side.

Each hot and cold fixture in the house will get its own dedicated waterline from the manifold.


The below graphic should help you get a better idea about how a drain, waste and vent system is set up for a small house.

waste lines

Planning a DWV (drain,waste, and vent) system is quite easy especially if you can use PVC or ABS pipe instead of galvanized lines. Remember, septic lines have to be vented to create a balance of atmospheric pressure in the lines. Without proper venting, water and solids won't run freely into the sewer.

dwv diagram

This is an illustration of a waste stack to show how the water and vent lines work together. The main waste line will be a 3-inch line minimum. This will go to the septic tank or the city sewer. Most waste water lines will be 2-inch lines and most vent lines will be 1 1/2-inch lines.

This is a diagram to show how copper pipes work for water lines. There are usually one hot line and one cold line. The copper branches off with many tees each time it gets to a fixture.

plumbing diagram

This diagram shows how each waterline and septic line connect to each fixture in a bathroom where copper pipe or galvanized pipe is used.

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Next, installing a water manifold