4 Things You Need to Know Before You Build Your Rainwater Collector

We have been receiving a lot of questions recently on rainwater collection systems. These systems are great for the conservation-minded, and those wanting to save on their monthly water bill. If you are serious about building one, there are also several resources and videos online that can help you.
However, before you begin, there are some things you should consider. Below I have listed 4 things you need to think about before you begin your project. For your convenience, I have also included a handy infographic at the bottom of this article that details these steps so you can get started right away.

 First, you need to estimate how much water you will need and how you are going to be using it. Are you going to use the water for landscaping purposes only? Or is the water going to be used for household use and watering livestock or animals? Regardless, you need to estimate how much you use each month to determine how much you will need. You can do this by using a water usage calculator like this one. This one only took me a minute to complete before I had an estimate.

Second, estimate the monthly rainfall averages in your area. The good news is, this has been done already for you. Here is a link to a site that is a weather database called WeatherDB.com This link shows the historical averages for the Midland, TX area. The site is very detailed, and not only shows averages by month for any given area, but it also includes daily record high and low precipitation as well as average annual rainfall. This will give you a good idea on how much rain to expect in a given month.

Lastly, you can determine how much storage you will need, by determining how much of this rainfall you expect to capture from your roof. This is a simple calculation, just take the length and width of your roof and convert to inches (Ex. Length= 50ft. x 12in. Width=30ft. x 12in.). Take the results and multiply them together to get the area(Ex. Length=600in. x Width=360in.). Multiply that number times the inches of rain (Ex. 216000 x .5in.). Then all you have to do is convert the cubic inches into gallons. You can do this by Googling “Convert cubic inches to gallons”, and Google will give you a conversion calculator to plug in your cubic inches. In this case, I plugged in 108000 inches the example came out to 467.5gallons. That means for ½” of rain I should get close to 467 gallons off my roof. Remember this is just estimate. Something I can work from to figure how many gallons I will approximately be capturing. Realize, I am not going to be capturing every ounce of rain. The point is, I should never get more than that for that amount of rain.

Also, as a side note, make sure you plan on putting your tank on an elevated surface and placing a spigot in the bottom. This is so that you can get as much out of the bottom as possible. Otherwise you could end up with several gallons in the bottom of your tank that you are unable to retrieve. We can do this for you, but if you plan on doing it yourself, make sure you have all the right parts. For a related article, see this story of how we helped the Aphasia Center of Midland set-up their Rain Collection system.
As always, if you need advice, help, or supplies please call us at 432-682-6584


Rainwater collection infographic