Cistern sizing calculator
How big a water tank do you need to keep the household running between deliveries (or rain events)? Tell us how many people, how much they use, and how long you want the tank to last.
Result
- Recommended cistern
- Nearest standard size
Sizing logic. Tank size = people × gallons-per-day × autonomy days. The result is the minimum useful capacity — most folks oversize by 20-30% for monsoon catchment storage and surprise visitors.
Tank shopping. Common AZ off-grid sizes: 1,500g (small cabin), 2,500g (small home), 5,000g (full home with garden), 10,000g (homestead with livestock). Polyethylene is cheaper but UV-degrades — paint it or shade it. Concrete is permanent and frost-proof but 2-3× the cost.
Recommended gear
Affiliate links — Plotnode may earn a commission from purchases at no extra cost to you.
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Amazon100-gallon portable water storage bladderEasy starter cistern or buffer tank. Folds flat when empty, packs into a truck bed.
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AmazonWASSERMANN 12V RV water transfer pumpSelf-priming, 5 GPM at 55 PSI. Move water from cistern to fixtures without grid power.
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AmazonSimPure whole-house sediment filter10"×4.5" big-blue housing. First-stage filter for any cistern feed before fine filtration.
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