About RainSave

Catching rain sounds simple — put a barrel under a downspout — but sizing a system properly, estimating how much you can actually save, and knowing where the water in your house goes all take a bit of arithmetic most people never get around to doing. RainSave exists to make that arithmetic quick, so you can decide whether a rain barrel, a greywater setup, or a few fixture swaps are worth it for your house before you spend a weekend or a paycheck on them.

Rather than long articles you have to wade through, the site is a set of small, single-purpose calculators, each aimed at one real question. The Rain Barrel Calculatorturns your roof area and local rainfall into a realistic harvest estimate and tells you how many barrels you’d need to catch it. The Household Water Use Calculatorbreaks down where an average home’s indoor water goes — showers, toilets, faucets, laundry, and dishes. The Leak Drip Loss Calculatorturns an annoying drip into a gallons-per-year figure that’s hard to ignore. The Irrigation Timing Calculator works out how long to run a sprinkler or drip line to hit a weekly watering target without guessing. The Greywater Calculator estimates how much shower, sink, and laundry water a household could realistically reuse for irrigation. And the Water Savings Calculator converts gallons saved into dollars saved on a water bill.

Beyond the calculators, the blog and learnsection cover the reasoning behind the numbers — how a first-flush diverter keeps roof grit out of a cistern, which fixtures are worth replacing first, how ancient aqueducts and qanats moved water for miles without a single pump, and what greywater can and can’t safely be used for around a home — and the museum is a browsable collection of the cisterns, aqueducts, wells, and modern systems that carried this idea through history, with every entry, image, and fact drawn from Wikipedia and Wikimedia Commons.

A few things worth stating plainly. RainSaveis independent and not affiliated with any water utility, plumbing manufacturer, or local building authority. It is supported by advertising, which is how the tools stay free with no account required. Every calculator here is a planning aid built on commonly cited engineering rules of thumb, not a substitute for a site assessment, a licensed plumber, or your local plumbing code — rules on rainwater storage, cross-connection, and greywater reuse vary a great deal by city and county, so always confirm what’s permitted before you install anything. If a tool looks wrong, or there’s a calculator you wish existed, the contact page is the place to tell us.