Collecting Rainwater - Is It Worth It?
Rainwater collection barrels are easy to set up and you might even get a rebate for purchasing them.
By: Annie
Here in the San Francisco Bay Area we often grumble about summer weather (we’re in a drought! It’s fire season!) and winter weather (now we’re drowning!) and it can be hard to imagine the opposite season when you’re dying of heat stroke or watching for flooding. However, saving all that water that falls from the sky can be a very neat way to keep your summer-dry garden looking a little greener, and with laws restricting water use for landscaping becoming tighter every year, using potable water on landscaping just feels like something we need to stop doing.
We have a drought tolerant ornamental garden at home (of course!), and we set the plants up for maximum success in surviving wet winters by planting them in raised beds to increase drainage. Occasionally a few of them can get positively shriveled in summer if they go more than a few weeks without a sip of water. (Yes, by “normal” plant standards that’s a tiny amount of water, but we’re into water conservation so we still feel guilty)
What we learned
In the last few years we have started collecting rainwater from our roof. And we learned a lot!
First, we discovered how easy it is. A simple system of six 55 gallon barrels located on our hidden side yard was very straightforward to set up, and one of the downspouts from our gutters feeds right into it. A watering can can be put under a spigot at one end of the daisy-chained barrels and voila!
Second, we found out how much water you can collect. Our roof is about 1350 square feet, but the section we collect rain off is about ⅓ of that area. For every 1” of rain that falls and 1,000 square feet of roof about 620 gallons are generated. Meaning, you can capture about 0.62 gallons per square foot of roof.
ALL of our barrels were filled to overflowing in the first rain storm of the year - that’s 330 gallons. We could have filled 12 barrels easily. We knew more rain was coming, so we used some of the water for outdoor tasks like cleaning out garbage cans, watering potted plants, and sluicing off a dirty car. The next storm was here a few weeks later and again the barrels filled overnight to capacity.
Third, we learned how long that water will last. We don’t water our garden at all in the rainy season, and some of our gardens never get watered at all. But after the last rainstorm in our area - usually in April - we let the ground dry out until about May. At that stage some plants that are just getting established will get hand watered about once a week, or every other week. And we always have hundreds of plants in pots we’re preparing for customers or for community gardens that do need water. With that rate of use, our 330 gallons of water will last until about August and if we add a couple more barrels, it should get us through the entire year until the next rainy season.
What’s the cost?
55 gallon barrels are inexpensive to buy, and purpose made rain barrels are a little more, but you can often get a rebate from your local water agencies when you buy these - up to $200 in our area. The rest of the parts needed (connecting hoses, spigot, wood to build a stand for the barrels etc) were very inexpensive. One can certainly spend more for custom systems, but if you’re handy, it can be a quick and durable system to set up. If you’re not handy, we can set one up for you!
How much can I save?
Our water bill is reduced by over 20% per month when we’re using rainwater for plants, but we really don’t use a huge amount of water anyway (xeric plants!). It may take a while to pay for the system but that’s not the point - we’re in it for the good of the environment, which is the same reason we create gardens with drought tolerant and native plants,
What else can I do with rain water?
Our local city ordinances only allow water features to use recycled or recirculated water, so a great way to make use of rainwater is to use it in a small wildlife water feature. Alternatively, you can create a rain garden to take rainwater away from your home’s foundations and return it to the water table - there’s even a $300 rebate for that in our area. Similarly, replacing your lawn with drought tolerant plantings can net you a rebate of up to $4 per square foot from your local water conservation agencies.
So next time you’re complaining about the rain, remember summer - and plan ahead by saving water. And by planting drought tolerant, native or xeric plants.
Check the rebates in your area: https://bawsca.org/conserve/rebates