How to calculate required HP for a water supply pump ,booster pump , sump pump in a residential building (3B+G+13+R)?

The general formula to find the required hp for pump is as follows.

Bhp = (USGPM X Head) / (3960 x Motor Efficiency x Pump Efficiency)

When you get the answer by above formula, multiply the result by 1.2 to convert the bhp to hp.

Energy imparted to water by the pump is called water horsepower - and can be calculated as

Pwhp = q h SG / (3960 μ)    (1)

where

Pwhp = water horsepower (hp)

q = flow (gal/min)

h = head (ft)

SG = 1 for water Specific Gravity

μ = pump efficiency (decimal value)