Our Water Tank Size Calculator helps you work out exactly how much water storage a home or building needs. Enter the number of people, choose how much water each person uses in a day, and decide how many days of backup storage you want. The calculator gives you the total storage required in litres, a recommended standard tank size, and ready tank dimensions for both rectangular and cylindrical tanks.
It is useful for homeowners planning a new house, architects and interior designers sizing building services for a project, and students learning how water supply is planned in residential buildings across India, where supply is often intermittent and storage does most of the heavy lifting.
How Much Water Does a Person Need Per Day?
The planning figure used in India comes from IS 1172, the code of basic requirements for water supply. For homes with full flushing, the standard is 135 litres per person per day. That figure covers drinking, cooking, bathing, flushing, washing clothes, and cleaning the house. Homes that use water carefully can plan on 90 litres per person, while premium homes with more bathrooms, fittings, and appliances are often planned at 200 litres per person per day.
The basic formula used is:
Total Storage Required = Number of People × Daily Use Per Person × Days of Storage
Once the storage is known, tank dimensions follow from volume. One cubic metre holds 1000 litres, so a 2000 litre tank needs 2 cubic metres of internal volume. At a water depth of 4 ft, that volume works out to a rectangular tank of roughly 5.1 ft × 3.4 ft, or a cylindrical tank of roughly 4.7 ft diameter. The calculator above works out both options for your own numbers.
On real projects, keep 150 to 200 mm of freeboard above the water level, and remember that an underground sump and an overhead tank solve different problems. The sump stores bulk water as it arrives from the supply line, and the overhead tank feeds the home by gravity through the day. Most Indian homes use both, and each one is sized from the same daily requirement.
Where Can You Learn Building Services and Estimation Properly?
Tank sizing is one small part of building services, the subject that decides whether a well-designed building actually works well day after day. ASDAV courses in architecture, interior design, Revit, and BIM teach water supply planning, material estimation, and drawing-based quantity work the way it is done on real projects. Explore the ASDAV courses and masterclasses to build these practical skills step by step.
