Well water calculators

Millions of American homes get their water from a private well, and the owners are responsible for its pump, tank and treatment. The calculators here cover the parts that are easy to get wrong.

The pressure tank is the first. A tank that's too small makes the pump start and stop every few seconds, which wears it out. Size the tank from your pump's flow rate and horsepower, set the air pre-charge correctly, and the pump runs long enough each cycle to stay cool. Well water also tends to be harder and more likely to carry iron than city water, so the water softener calculators apply here too.

Which calculator do I need?

If you want to know	Use
What size pressure tank for my well	Well pressure tank size calculator
Hardness on a well	Water hardness converter
A softener for well water	Water softener size calculator

Water pressure gauge in psi on a plumbing manifold

Well Pressure Tank Size Calculator

Tank size and pre-charge from your pump's gpm, horsepower and switch setting.

Row of resin treatment tanks with control valves and blue piping

Water Softener Size Calculator

Grains you need from your household and hardness, at your real salt setting.

Water sample in a glass beaker with a pipette

Water Hardness Converter

gpg, ppm, mg/L, mmol/L and German or French degrees in one step.

FAQ

How often should I test my well water?

The EPA and most state health departments advise testing at least once a year for bacteria, nitrates and anything common in your area, and after floods or repairs.

What size pressure tank do most homes have?

Many homes use tanks between 20 and 86 gallons. The right size depends on the pump's flow rate and horsepower, not the size of the house.

Does well water need a softener?

Only if it's hard. Test hardness and iron first. If it's above about 7 gpg, or has iron, a softener or iron filter is worth pricing.

Sikander Mushtaq

Founder of HomeWaterMath. Builds and checks every calculator.

Last updated: Oct 20, 2026 · Editorial policy