Sizing Water Supply

Fixture Unit Table for Determining Water Pipe & Meter Sizes

How do you size a water supply line?

Quote from Youtube video: Home can provide nine gallons per minute to your home while a one and a quarter inch line will provide 16 gallons per minute that's a fifty six percent difference.

What size should my water line be?

In most cases, the main pipeline from the street to your home is either 3/4 or 1 inch in diameter, supply branches use 3/4-inch-diameter pipe, and pipes for individual components are 1/2 inch. Remember that water pressure decreases by a half-pound per square inch for every foot pipes extend above your water supply.

How is water supply calculated?

The total theoretical demand for a water supply system can easily be calculated by adding known maximum demand for all fixtures in the system.



Total Theoretical Water Flow and Expected Flow.

How many fixtures does a 1/2 water line have?

For our example, our 1-inch pipe can have up to 30 fixture units, our 3/4-inch can have up to 14, and our 1/2-inch can have up to 4.

Can you increase water pressure by reducing pipe size?

Because if the diameter of a pipe decreased, then the pressure in the pipeline will increase. As per Bernoulli’s theorem, pressure can be reduced when the area of conveyance is reduced. In the narrower pipe, the velocity can be high, and pressure can be higher.

Which pipe is best for water supply?

Cross-Linked Polyethylene (PEX)



Cross-linked polyethylene, or PEX for short, is a type of plastic that is commonly used for hot and cold water supply lines. It is extremely flexible, can easily curve around corners and obstructions, and has high durability and low corrosion.

What size supply line is needed for a kitchen faucet?

The two most common are 3/8- and 1/2-inch compression or male pipe thread. Faucets connectors aren’t completely standardized, but most have 1/2-inch male pipe thread connectors.

What is the minimum size water supply to a water closet?

604.5 Size of Fixture Supply

How far can you run a 1/2 water line?

A 3/8-inch line is sufficient for lengths up to 250 feet; 1/2-inch line will deliver adequate water pressure up to 350 feet; and 3/4-inch tubing is necessary to run a 500-foot line.

How many fixture units can a 2-inch drain handle?

710.1 Maximum Fixture Unit Load

Do I need a vent for every drain?

Without getting too far into building science, a general plumbing rule of thumb is that every drain needs a trap, and every trap needs a vent. All those traps and drains are designed to prevent sewer gas from entering your home.

How many water closets are needed for a 3 inch drain?

There is one answer. The International Plumbing Code requires 5 Drainage Fixture Units in a bathroom group. It’s good for 20 DFU’s or 4 bathroom groups.

How much water can a 4 inch drain pipe carry?

A single 4″ or larger pipe may be used (a single Drainage Zone system).



STEP 3: Choose the number of drainage zones.

How many gallons per hour can a 4 inch pipe handle?

Metric PVC Pipe

How much water can a 2 inch drain handle?

1106.2 Size of Storm Drain Piping