How to calculate the ideal capacity
Minimum capacity = number of residents × consumption per person/day × reserve days. Average daily consumption per person is commonly estimated between 150 and 200 liters, but it varies quite a bit by habits and climate.
How many reserve days?
It's common to size the tank for at least 1 full day of reserve, to cover occasional supply interruptions. In areas with unstable supply, 2 days is safer.
Common commercial sizes
310 L, 500 L, 1,000 L, 1,500 L, 2,000 L, 3,000 L, 5,000 L and 10,000 L are the most common tank sizes on the Brazilian market (other markets may offer different standard sizes). The calculator suggests the smallest commercial size that meets the calculated minimum capacity.
Example
4 residents, 150 L/person/day, 1 reserve day: minimum capacity = 600 L → suggested commercial size: 1,000 L.
Frequently asked questions
What's the average water consumption per person?
It's commonly estimated between 150 and 200 liters per person per day, but this varies with habits, climate and region.
Why does the calculator suggest a "round" commercial size?
Because water tanks are sold in standardized sizes — the calculator rounds up to the smallest available size that meets your needs.
Is 1 reserve day enough?
For most homes in areas with stable water supply, yes. In areas with a history of water shortages, consider 2 days.
Does this account for pool or garden water use?
Not directly — for additional uses, manually add the estimated extra consumption when calculating.