Water Storage Tank Sizing Calculator
How big a water storage tank do you actually need? This calculates your minimum and recommended capacity.
Basic off-grid use: 5–15 gal/person/day. Full comfort: 20–50. US average (not relevant for off-grid): 80–100.
7–14 days is standard. 30 days for remote locations with unreliable supply.
Your Results
Daily Water Use —
Minimum Tank Size —
Recommended Tank Size —
Common Tank Size to Buy —
Add 10–15% for system dead space and cleaning reserve. Polyethylene tanks (Norwesco, Chem-Tainer) are the standard for off-grid water storage.
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— filtration, collection, and pump options