The Hazen-Williams equation is an empirical expression used for calculating friction losses in pipes. Use of the Hazen-Williams equation requires the selection of an appropriate Hazen-Williams roughness coefficient (Coming Soon). These coefficients are widely available and we will be compiling a list to be included on this site. Use our Hazen-Williams calculator(coming soon) to quickly evaluate friction losses. The variables in the Hazen-Williams formula are explained as follows:

f = friction head loss if feet of water
v = velocity in feet per second
L = length of pipe in feet
D = diameter of pipe in feet