Freshwater rain falls on your house every year and flows into the sewer systems and rivers and back to the oceans. But you can capture that rain and use it. Then, you will need less water from the water company. To catch rain, set up rain gutters along your roof that funnel the water down into a rain catchment tank that sits next to your house. It is easy to set up the watering for your garden to use the rainwater in the tank. It’s also easy to hook up a hose to wash your car, driveway, or even your dog. The next level is to set it up to use rainwater in your house for non-potable uses, like toilet flushing and clothes washing. Finally, you can use it for all water needs, such as sink water for washing dishes and even drinking and cooking water. Potable water must be filtered and treated properly before use.
You can calculate how much water you can collect per year by taking the average annual rainfall per year in inches in your area and the square footage of your roof. For every 1” of rain for 1 square foot of roof, you can collect .623 gallons. Multiply rain inches by square footage, and multiply by .623 to get the total gallons collected per year. Determining how often it rains throughout the year and your usage needs, you will be able to figure out how large of containers you need.
A bonus is that this is free water, so you will save on your water bill.