Downstream versus upstream pipe replacement

Plumbing · Flow and Pressure · printed page 258 (PDF page 259)

Book index entries

Pipe Replacement in Plumbing System – Downstream vs Upstream Plumbing – Downstream vs Upstream Pipe Replacement Supply Plumbing – Downstream vs. Upstream Pipe Replacement Flow and Pressure of Water in Supply Plumbing Supply Plumbing – Flow and Pressure Water Flow – and Pressure in Supply Plumbing

Text in the illustration

installing larger diameter piping in the downstream sections is just as effective as replacing the upstream sections
from street
flow
3/4" pipe
1/2" pipe
at fixture
60 PSI
50 feet (pressure drop = 3 PSI)
57 PSI
50 feet (pressure drop = 15 PSI)
42 PSI
45 PSI

Generated explanation

Two schematic water-supply runs compare the effects of locating larger-diameter piping upstream versus downstream between the street and a fixture. The upper run has 50 feet of 3/4-inch pipe followed by 50 feet of 1/2-inch pipe, with indicated pressures decreasing from 60 PSI to 57 PSI and then 42 PSI. The lower run reverses the pipe sizes, with pressures decreasing from 60 PSI to 45 PSI and then 42 PSI. Each 3/4-inch section has a labeled pressure drop of 3 PSI, while each 1/2-inch section has a drop of 15 PSI. The illustration explains that installing larger piping downstream is just as effective as replacing upstream sections in the configurations shown.

Components

water-supply piping 3/4-inch pipe 1/2-inch pipe pipe size transition fittings