Water Tank Size Calculator
Work out the storage tank volume needed for a household or site from daily use and days of reserve.
Compare Your Options And Get Clear Answers
Work out the storage tank volume needed for a household or site from daily use and days of reserve.
Water Tank Size Estimator
Enter your numbers below for an instant estimate.
How It Works
Key concepts behind this calculator
Enter Values
Fill in each field with your own numbers.
Calculate
Results update as you change the inputs.
Review
Read the breakdown and the explanation.
Adjust
Change values to compare scenarios.
Water Quick Guide
Typical values for reference.
| People | L/person | Days | Tank L |
|---|---|---|---|
| 1 | 150 | 2 | 360 litres |
| 4 | 150 | 2 | 1,440 litres |
| 6 | 150 | 3 | 3,240 litres |
| 20 | 150 | 3 | 10,800 litres |
| Rule of Thumb | Check inputs | Use as a guide | Round sensibly |
Water Tank Size Calculator FAQ
Answers to common questions about this calculator.
Multiply daily use by the days of storage you want, then add a margin.
Around 130 to 160 litres a day in the UK.
Tank = people x litres per person x days x (1 + margin).
It is an estimate based on the inputs you enter. Check real quotes, labels or official guidance for important decisions.