Enter the total height of the water tower into the calculator to determine the generated water pressure. This calculator can also calculate height when given pressure.
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Water Pressure Elevation Formula
Static water pressure changes with vertical height only. Horizontal distance does not matter.
ΔP (psi) = 0.4335 × SG × h (ft)
- ΔP = pressure change in psi
- 0.4335 = psi added per foot of fresh water column
- SG = specific gravity of the water (1.000 fresh, 1.025 sea, 0.983 hot)
- h = vertical height in feet
Rearranged to solve for elevation head:
h (ft) = P (psi) / (0.4335 × SG)
Final pressure at a second point:
P_final = P_start ± (0.4335 × SG × h)
Use minus when the second point is higher than the start, plus when it is lower. These equations are static. They ignore pipe friction, fitting losses, flow velocity, and pump effects.
Reference Tables
Quick conversions between vertical height and pressure for fresh water (SG 1.000).
| Height | Pressure (psi) | Pressure (kPa) | Pressure (bar) |
|---|---|---|---|
| 1 ft | 0.43 | 2.99 | 0.030 |
| 10 ft | 4.33 | 29.9 | 0.299 |
| 25 ft | 10.84 | 74.7 | 0.747 |
| 50 ft | 21.68 | 149.5 | 1.495 |
| 100 ft | 43.35 | 298.9 | 2.989 |
| 1 m | 1.42 | 9.81 | 0.098 |
| 10 m | 14.22 | 98.1 | 0.981 |
How to read a final pressure number for typical household plumbing.
| Pressure (psi) | What it means |
|---|---|
| Below 0 | Source cannot lift water that high |
| 0 – 20 | Too low for most fixtures |
| 20 – 40 | Workable, but weak at upper floors |
| 40 – 60 | Standard target range |
| 60 – 80 | Acceptable upper end |
| Above 80 | Code generally requires a pressure regulator |
Worked Example
You have 60 psi at the street tap. A second-floor showerhead sits 22 ft above that point. What is the static pressure at the showerhead?
- Pressure lost to elevation: 0.4335 × 1.000 × 22 = 9.54 psi
- Static pressure at the showerhead: 60 − 9.54 = 50.46 psi
That is before any losses from pipe length, fittings, and flow. Expect 5 to 15 psi more loss once water is moving.
FAQ
Does pipe diameter change static pressure? No. Static pressure depends only on vertical height and fluid density. Diameter affects flow rate and friction loss, not the standing column pressure.
Why 0.4335 psi per foot? One cubic foot of fresh water weighs 62.4 lb. Spread over 144 square inches, that is 0.4335 psi per foot of height.
Should I use hot or cold water settings? Use hot only when calculating a tall hot-water column. The density change is small, around 1.7 percent at 140°F, and rarely matters for residential work.
How high can a given pressure push water? Divide psi by 0.4335. For example, 40 psi lifts fresh water about 92 ft vertically with zero flow.
