Water Tank Calculator

Most people size their water tank by guessing.

They ask a neighbor. They ask the plumber who's trying to sell them the biggest tank possible. They Google it and get a generic "150 liters per person per day" answer with zero context about their actual supply situation, roof structure, or pressure needs.

Then they either buy too small and run dry every other day — or buy too big, crack their roof slab, and wonder why their shower pressure is still garbage even with a massive tank sitting up there.

The problem isn't the tank. It's that nobody's doing the actual math.

That's exactly why WaterTankCalculator.com exists.

65+ free calculators. No signup. No paywall. Built on real engineering standards — ISO, ASTM, BS — not guesswork.

Need to know your tank volume? Done in 10 seconds. Want to know if your roof can handle a full 5,000L tank? There's a calculator for that. Trying to figure out why your shower pressure is weak even though your tank is full? That's a height problem — and there's a calculator for that too. Sizing rainwater harvesting for your roof catchment? Chlorine dosage for disinfection? Crop water requirements for irrigation? Emergency stockpile for 14 days off-grid?

All of it. One site. Free.

👉 https://watertankcalculator.com/calculators/pressure/water-pressure-calculator