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Mar 25

How to Water Your Garden With Rain Barrels

Posted on March 25, 2020 at 1:10 PM by Allan Warren

Rain barrels are great tools for reducing our personal impact on pollution running into Puget Sound. They can also be great tools to help make gardening easier. The trick is, how do you create an easy, convenient watering system from your rain barrels? Well, by trying out different methods over 4-growing seasons , I finally figured out a system that works and so hopefully this little tutorial will help you do the same.

Reducing Stormwater Pollution
Each year, we get about 40-inches of rain, which turns into 24,000 gallons of stormwater runoff for every 1,000 square feet of impervious surface, (roofs, driveways, decks). As an example, when you combine the square footage of the roof of my house, the roof of my shop, my driveway, my greenhouse, and my deck, our home's total impervious surface is about 2,500 square feet. That means our home produces ~60,000 gallons of stormwater runoff.Stormwater Runoff Graphic Every. Single. Year.

Stormwater itself isn't a bad thing, it's all the stuff stormwater picks up on it's way to Puget Sound that's the problem. All the excess fertilizer from our lawns, all the bacteria from our pet poop, all the liquids or shavings coming from our cars, then once it hits the street, all the other nastiness that lives there. So, one of the best things we can do is limit the amount of stormwater that makes it off our property to begin with. Rain barrels help do this by storing stormwater during storm events, then slowly dispersing the water once the storm has passed, reducing the peak flows of runoff. To be clear, rain barrels don't mitigate 60,000 gallons a year, but their one tool that helps; rain gardens, pervious pavement driveways, and cisterns are other examples of tools that help. Now that I have my watering system figured out, I plan on putting a large cistern at the front of my house to water my other garden with.

Watering Your Garden
To start, you'll need a few things:
  • Rain Barrels - these can be purchased through any number of outlets, such as Amazon, Home Depot, Lowes, etc. Our preferred vendor is www.naturalrainwater.com/. We usually work with Dan Borba every spring and fall to host rain barrel workshops, which offer the chance to build your own rain barrel at a deep discount. Unfortunately, the COVID-19 outbreak has put this April's workshop on hold, so if you want to get started immediately, you can just buy one. (One of Dan's how to videos is embedded at the bottom of this post)
  • Pressure Pump - this is the key to the watering system. There are a handful of options toPressure Pump choose from, but the one that I bought for about $100, is the SEAFLO 33-Series Industrial Water Pressure Pump w/Power Plug for Wall Outlet - 115VAC, 3.3 GPM, 45 PSI. This has worked great for pulling water from two rain barrels since I installed it last year, including over the winter months; (though you'll want to run the water out of it before any hard freezes.)
  • Drip System Hoses and Adapters - You'll need to start with 1/2 inch hose such as this to run from the rain barrels to the pump, (can also be purchased as a kit with a drip system). These can be connected with adapters such as this, and if you're running water to the pump from multiple barrels such as my system you also need to add a T- adapter such as this as there's only one inlet to the pump. Exact sizes of all this will vary by your own connection sizes and preference. From the outlet you can run water in a variety of ways: soaker hoses, regular drip systems, or even adapt a drip system to be an overhead sprinkler system such as what's shown in the video above.
  • Automatic Timer: The pressure pump doesn't have an on/off switch on it, so you could manually go plug it in for 10 minutes or so every day to run, or you can buy an automatic,IMG_0203 programmable timer. Do not buy a battery powered irrigation timer, I made this mistake and it doesn't work for these purposes. Those are essentially just check valves, they work with a drip system that is hooked up to your outdoor spigot, but only because there's already pressure in that system. You need an outdoor heavy duty digital programmable timer that plugs into a household outlet such as the one pictured to the right and linked here. You can plug an extension cord into it that then runs to the pressure pump. I program mine to run for about 10 minutes every other day in the summer, then about 15 minutes everyday in the winter. 
It will likely take some trial and error to get it all working properly, but hopefully not 4-years worth like I had! We're here to help too if you want some advice or run into any troubles, just email me at AllanW@PierceCD.org if you need some help. Good Luck!

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