Household water tank size calculator
Estimate the tank that keeps your family supplied through water cuts or late deliveries.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter people, use per person per day, storage days and extra reserve.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Capacity = people × liters per person per day × storage days × (1 + reserve).
Example
Inputs: People = 6, Use per person per day = 200 L, Storage days = 2, Extra reserve = 10 %. Result: Capacity needed: 2,640 L; Cubic meters: 2.64 m³; Nearest common tank size: 3,000 L.
Limits and caveats
- 200 liters per person per day is an editable default, not an official figure; household use varies widely.
- Suggested sizes are common market sizes and differ between makers.
Questions about this tool
What tank does a family of 6 need?
At 200 L per person, 2 days of storage and a 10% reserve you need 2,640 L, so a 3,000 L tank fits.
How do I find my use per person?
Take the monthly water bill in m³, multiply by 1,000, then divide by the number of people and by 30.
Why add a reserve?
Some water sits below the outlet and cannot be drawn, and guests or hot days raise use.