When we watch the evening news, the weatherperson will oftentimes say things like “X city received an inch of rain today”, which does not really sound like all that much. We imagine a single inch of rain in a small puddle somewhere it seems rather insignificant. But what if you knew that a single inch of rain could allow you to collect hundreds and hundreds of gallons of water, if not more? Now that one inch of rainfall seems like a lot more!
Let’s take a look at a hypothetical example to see just how much water we can collect from rainfall. If you have 1,000 square feet of roof on your house, and it rains just 1 inch, you can collect 600 gallons of water to be used in your garden, for washing your car, or just for drop irrigation around your property. That’s 600 less gallons you have to pay for and use from your town water supply! So how can you do the math for your own roof? Just multiple the square footage of roof space you have available X 0.6 gallons per square foot per inch of rain, and you can see how much water you can collect from each inch of rain that falls.
So if you have 2,500 square feet of roof available for water catchment, and a single inch of rain falls one day, we see that:
2,500 X 0.6 = 1,500 gallons of water can be harvested for future use…from only one inch of rainfall!
On average, Americans use about 69 gallons of water per person per day for bathing, cooking, cleaning and flushing toilets – and is just for indoor water use and does not account for any watering/car washing going on outside. That amounts to about 2,100 gallons a month for each person – or only slightly more than you might be able to collect off your roof in a single rainstorm. Sure, you might not want to use that water for your showers or drinking water, but it can be done…and many people are putting cisterns in their yard and systems in their house to be able to do so. But if you are not interested in doing that and just wanted to use it outside, using a rain barrel or two under your downspouts can make a big difference in your monthly water usage and bill. Let’s take a look at one more example to see how much of a difference collecting rainwater can make – If you live in Boston, Massachusetts, which gets an average of 42.53 inches of rain per year, and you live in a house with 1,000 square feet of roof space…
1,000 X 0.6 X 42.53 = 25,518 gallons of water collected each year in Boston, MA.
That’s a lot of water that you can save (and money!) by hooking up and using rainwater catchment systems at your house. It’s a big return for a very small investment, and I bet you will hear something different the next time the weatherperson says “X city received an inch of rain today”!