HOW TO USE IT
How to use the Water Pressure and Pipe Loss Calculator
- 1
Start with the static pressure: Measure or use the supply pressure at the meter. That is the starting point before any loss.
- 2
Estimate the friction loss: Longer pipes, smaller diameters and higher flow all increase friction. A common friction model is the Hazen-Williams equation.
- 3
Add elevation and fittings: Every vertical foot of rise subtracts pressure, and each elbow, tee or valve adds a small friction loss.
- 4
Compute the remaining pressure: Subtract friction, elevation and fittings from the static pressure. If the result is low, the run needs a bigger pipe. Use the Water Pressure and Pipe Loss Calculator.
THE MATH
Water pressure calculation method
Add friction loss, elevation and fittings to the total drop. A 60 psi supply over 100 ft of 1-inch pipe at 8 gpm with 5 fittings and a 10 ft rise loses about 6.8 psi, leaving about 53 psi.Longer pipes, smaller diameters and higher flow all increase friction. A common friction model is the Hazen-Williams equation.
PRACTICAL EXAMPLE
Worked example for Water pressure
Add friction loss, elevation and fittings to the total drop. A 60 psi supply over 100 ft of 1-inch pipe at 8 gpm with 5 fittings and a 10 ft rise loses about 6.8 psi, leaving about 53 psi.
FAQ
Frequently asked questions
How do you calculate water pressure loss?
Add friction loss, elevation and fittings to the total drop. A 60 psi supply over 100 ft of 1-inch pipe at 8 gpm with 5 fittings and a 10 ft rise loses about 6.8 psi, leaving about 53 psi.
What should I verify before using the result?
Low pressure at a fixture is often a pipe-sizing problem, not a supply problem. Check the run before blaming the utility.
Is this a final quote or design?
No. Use it as a planning estimate, then confirm measurements, local rates, product requirements, permits and jobsite conditions before bidding or building.