A simple way to estimate the right tank size is by calculating how much rainwater your roof can collect. Multiply your roof’s surface area (in square feet) by your average annual rainfall (in inches), then multiply by 0.62, this gives you the total gallons you could collect in a year. For example, a 1,000 sq ft roof with 30 inches of rainfall can collect around 18,600 gallons annually. From there, we can help you choose the right tank size based on your water use and how much storage you want on hand, whether you're using it for irrigation, home use like toilets or laundry, or even potable water with the proper filtration upgrades.