The system's two jobs
★Keep enough PRESSURE everywhere, and keep contamination OUT.
A disinfectant residual + cross-connection control protect the water.
Components
Gate valve = on/off, isolates a section. Fully open or fully closed.
Check valve = one-way; stops backflow (e.g. on a pump discharge).
Curb stop = shuts off one customer's service.
Altitude valve = controls a tank's level; stops overflow.
Thrust block = concrete behind a bend/tee/dead end to resist thrust.
Blow-off = drain/flush a dead-end main.
Pressure, storage, backflow
psi = feet x 0.433 | feet = psi x 2.31
Elevated tank adds pressure by its height, no pump running.
PRV lowers/holds pressure for a low zone.
★Backflow prevention (air gap, vacuum breaker, assemblies) keeps used water out.
Pipe volume
gallons = 0.785 x D x D x length x 7.48
Change the pipe's inches to feet first (inches / 12).