Nine calculators, no strings
Every one of these gives you a number for your own house, from public federal data, with the source and the date printed next to it. None of them carries an affiliate link, and none of them asks for your email before it works.
What each one tells you
- 1.Household water planHow many gallons your household needs, and how long what you have would last.Source: Ready.gov, one gallon per person per day.
- 2.Rain barrel calculator, by stateGallons your roof catches per inch of rain, per month and per year, plus what overflows.Source: NOAA rainfall normals 1991 to 2020, USGS roof figure.
- 3.48-hour power plan for an apartmentWater in gallons, power bank in watt-hours, and the fridge clock for your household.Source: Ready.gov power outages, EIA outage hours.
- 4.30-day pantry, priced this monthWhat a month of food costs at today's federal average prices, scaled to the calories you want covered.Source: BLS average prices, USDA FoodData Central.
- 5.Generator or battery, by stateYour state's outage hours, a typical outage length, and the watt-hours your list actually needs.Source: EIA Electric Power Annual, data for 2024.
- 6.Water from air, by cityGrams of water per cubic metre of your air, and how much air one gallon really takes.Source: NOAA hourly climate normals 1991 to 2020.
- 7.Drought map, by stateYour state's five drought bands, the people inside them, and how the number moved in a year.Source: U.S. Drought Monitor, map week of 8 Sept 2026.
- 8.Water treatment dose, by containerHow much bleach, iodine or calcium hypochlorite for the container you have, how long to wait, and what none of it removes.Source: EPA emergency disinfection, CDC make water safe.
- 9.The blackout kit you already ownHow many gallons and how many hours the things already in your house cover, and the one gap left.Source: EIA residential energy survey 2020, EIA outage hours 2024.
The tool comes before the product, always
Most people arrive here knowing they want stored water and not knowing how many gallons. A calculator answers that in ten seconds, for free, and it answers it the same way whether or not you ever buy anything. That is deliberate: a site that makes you pay to find out what you need has already picked a side.
The money comes from the four product reviews, which say so on every button. If a calculator ever starts nudging you towards a product, we have broken our own rule and you should write to us.
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