📖 About This Category
What These Pressure & Height Calculators Cover
Water pressure is determined almost entirely by height. Whether your system relies on gravity or a pump, understanding the relationship between elevation and pressure is what separates a system that works from one that frustrates you daily. This category contains six calculators targeting every stage of that problem: finding out how much pressure your current tank delivers, sizing a pump to hit a target pressure, checking that gravity-feed flow is sufficient for your application, verifying that your tank structure can withstand hydrostatic loads, converting between pressure units for different trades, and calculating the exact minimum tank elevation needed for a functional shower.
These tools are used by homeowners sizing rooftop water storage, plumbers specifying pipe and pump combinations, civil engineers designing gravity irrigation systems, and anyone setting up an off-grid water supply. Each calculator gives instant results in the most common engineering units with no sign-up required.
🧭 How to Choose
How to Choose the Right Calculator
Start with: what problem are you solving?
If your system is gravity-fed and you want to know the pressure at a tap or outlet, use the Water Pressure Calculator. Feed it your tank height and you get instant bar/PSI/kPa results. This is the most commonly needed tool in this category.
You're buying or sizing a pump
Gravity alone isn't enough for many residential or agricultural setups. The Pump Head Pressure Calculator accounts for static lift plus pipe friction to give you the total dynamic head — the number on every pump datasheet. Use this before spending money on a pump.
You need to know if gravity-feed flow rate is sufficient
Pressure alone doesn't tell you whether enough water will flow. The Gravity Feed Flow Rate Calculator models head height, pipe diameter, and pipe length together to give you a flow rate estimate. If the result is too low, you need a pump or larger pipe — not a higher tank.
You're specifying or verifying a tank's structural integrity
The Hydrostatic Pressure Calculator tells you the pressure acting on any point in a tank's wall or base. Use it to verify that a tank you're purchasing or designing is rated adequately. Never skip this for large or deeply buried tanks.
You need to convert pressure units or verify a shower installation
The Water Column Pressure Calculator handles unit conversions between all common pressure formats. For shower installations specifically, the Minimum Tank Height for Shower Pressure Calculator removes all guesswork — give it your showerhead type and it returns a minimum elevation figure.
| Your Situation | Use This Calculator | Key Output |
|---|
| Gravity tank, check outlet pressure | Water Pressure Calculator | bar / PSI / kPa |
| Buying a pump, need head spec | Pump Head Pressure Calculator | Total dynamic head (m) |
| Check if gravity flow rate is enough | Gravity Feed Flow Rate Calculator | L/min or GPM |
| Design or verify tank wall rating | Hydrostatic Pressure Calculator | Pressure at depth (bar) |
| Convert pressure units | Water Column Pressure Calculator | m WC / in WC / bar / kPa / PSI |
| Gravity shower, check height needed | Min Tank Height for Shower Pressure | Minimum height (m / ft) |
❓ FAQ
Frequently Asked Questions
How do I calculate water pressure from a rooftop tank?
Water pressure from a gravity-fed rooftop tank is determined by the vertical height (head) of water above the outlet. The formula is: Pressure (bar) = Height (m) × 0.0981, or in PSI: Pressure (psi) = Height (ft) × 0.433. A tank positioned 10 metres above a tap delivers approximately 0.98 bar (14.2 psi) of static pressure. Use the Water Pressure Calculator to run this instantly.
What is the minimum tank height needed for a good shower?
Most conventional showerheads require a minimum of 0.1 bar (1.5 psi) to function — roughly 1 metre of head. For a comfortable shower, 0.2–0.3 bar is preferred, which means 2–3 metres of vertical distance between the tank outlet and the showerhead. Power showers and thermostatic mixer valves often need 0.5 bar or more, demanding 5+ metres of head. Our Minimum Tank Height for Shower Pressure Calculator handles this for any showerhead type.
What is the difference between static and dynamic water pressure?
Static pressure is the pressure in a system when water is not flowing — determined purely by the height of the water column. Dynamic (residual) pressure is the pressure at a tap while water is actually flowing. Dynamic pressure is always lower than static because pipe friction consumes available head. Our calculators produce static pressure values; for full dynamic calculations, pipe diameter and flow rate also need to be factored in, which the Gravity Feed Flow Rate Calculator handles.
How do I convert metres of water head to bar or PSI?
The conversion is: 1 metre of water head = 0.0981 bar = 1.422 psi = 9.81 kPa. So 10 metres of head produces 0.981 bar or roughly 14.2 psi. In reverse: 1 bar = 10.2 metres of head. The Water Column Pressure Calculator handles all these conversions in both directions automatically.
Pressure (bar) = Height (m) × 0.0981
Pressure (PSI) = Height (ft) × 0.433
Pressure (kPa) = Height (m) × 9.81
What pump head do I need to fill a rooftop tank?
The pump must overcome total dynamic head: vertical lift (static head) + pipe friction losses + any required delivery pressure. As a rough starting rule, add 20–30% to the pure static head to account for pipe friction in a typical residential installation. For example, a 10-metre lift with 20 metres of 25 mm pipe might require 12–13 metres of total head. The Pump Head Pressure Calculator handles this precisely based on actual pipe parameters.
What is hydrostatic pressure and why does it matter for tank design?
Hydrostatic pressure is the pressure exerted by a fluid at rest due to the weight of water above a given point. At the base of a full 2-metre-tall tank, the hydrostatic pressure is approximately 0.196 bar (2.84 psi). This matters because tank walls and base fittings must be structurally rated to handle this pressure — which increases linearly with depth. Underrated tanks can crack or fail at connection points. Use the Hydrostatic Pressure Calculator to determine pressure at any depth before specifying materials.