Water pressure gets quoted in four units — psi, bar, kPa and feet of head — and plumbing specs mix them freely. They all describe the same thing, so converting is just multiplying by the right factor. Here are the conversions, plus the benchmarks that tell you whether a reading is healthy.
The conversions
| 1 of this | equals |
|---|---|
| 1 psi | 6.9 kPa ≈ 2.31 ft of head |
| 1 bar | 14.5 psi = 100 kPa ≈ 33.9 ft of head |
| 2.31 ft of head | 1 psi (0.69 m per 0.1 bar) |
Water Pressure Converter
Enter a value in psi, bar, kPa or feet of head and read the rest, with the benchmarks to check against.
What is “feet of head”?
The height of a water column the pressure supports — the most physical of the four units. Every 2.31 ft of elevation adds 1 psi. It works both ways: a tank 20 ft above a faucet delivers about 8.7 psi (0.6 bar), and a pump must add 1 psi for every 2.31 ft it lifts — which is why tanks and pumps are often specified in head.
What’s normal household pressure?
US municipal supply typically arrives at 40–80 psi (about 3–5.5 bar / 300–550 kPa), and many codes cap it at 80 psi. Fixtures are happiest between about 30 and 60 psi; below 15 psi (1 bar) showers feel weak and some tankless heaters won’t operate, while sustained pressure above 80 psi strains hoses, valves and water heaters — a pressure-reducing valve is required above that.
Static vs dynamic pressure
Static is the pressure with no water flowing; dynamic is what remains while a faucet runs, after friction losses. A system can show a healthy 60 psi (4 bar) static and still deliver a weak shower if undersized pipework eats the pressure when flow starts — which is why pressure complaints are diagnosed with a gauge under flow, not just standing.
What water heaters are rated for
US residential water heaters are typically rated to 150 psi maximum working pressure, protected by a temperature-and-pressure (T&P) relief valve; elsewhere cylinders are rated 400 or 600 kPa with a matching control valve. Either way the relief valve must match the tank’s rating — an over-rated valve on a lower-rated tank is a burst waiting to happen.