Project: Rain Barrel

So Saturday my friend Al arrived at my doorstep with one of the stranger birthday presents I've ever received, a 55 gallon plastic drum. "This guy was selling them on Craigslist for like $20, so I bought two!" It was from the back dock of some kind of bakery and contained 'Maltitol', a sort of sugar-alcohol artificial sweetener. It was slightly sticky, and smelled of cupcakes.

Actually, as birthday presents go this one is pretty sweet. Part of our renewing out lease was an effort to cut down on our water bills. Get landlord to fix leaky things, put new guts in the toilet, etc.. A rain barrel was also on my mind. So seeing how it was Memorial Day weekend and we had nothing else going, Al and I hopped into the car and sped off to Home Depot.

Rain barrels are actually really easy to build. At its heart you need something to divert your rain gutters into the top, then something to filter leaves and bugs, then a spigot on the bottom. Finally, and most importantly, some kind of overflow setup (more on this later). The goal was to make it modular, so we could fix anything that went bad or was ill-thought-out. I wanted it to cause little or no damage to the existing gutter system, so I can put that back together when I eventually move. I also wanted the water to divert well away from my heating oil bunker, and still allow access to it. So we looked around the yard, looked around the garage, wandered around Home Depot for a while, and came up with this setup.


The gutter diverts (via some duct taped pipe fittings) to a hole on the top. In there is an atrium grate, with window screen rubber banded on to keep bugs out. The spigot is a threaded plastic electrical bulkhead, glued in with a bunch of Plumber's Goop glue. A garden faucet is screwed on that. The overflow is a 2" to 3" ABS coupler, glued in with more Plumber's Goop at a sloping angle. The overflow and main pipes were cut from an 8' section of 3" PVC that I used to protect my fishing rods during the move. The whole thing is propped off the ground by some sections of 4x4 that was left over from building the raised beds in the garden. All told, the barrel cost about $20. (Well, $40 if the barrel itself hadn't been a gift.) But how well does it work?

Do you know how many gallons of water pour off your roof every time it rains? A LOT. The guestimation formula is:

Roof Square Feet x 0.6 = Gallons of Water per Inch of Rain.

Based on City estimates, I'm going to say that rain gutter drains about 1/3 of my 1500 sq. ft. roof space, maybe 500 square feet. Which means that for every inch of rain 300 gallons fall on that part of the roof! Given that it rains about 37 inches annually in Seattle, that's 11,100 potentially useful gallons that otherwise go to the storm drain.

Here's where the overflow comes in. As we finished the project it began to drizzle. Soon we could hear a drip, drip, drip in the barrel. By morning, it was full. Completely full. 50 gallons. The overflow was draining nicely into the blackberries off on the side of the house. Guess this is why people put three or four barrels in series. But since it takes 1/6 of an inch of rain to fill the barrel, and it rains about 150 days a year here, I don't think I'll run out very often. My garden's not huge anyway, and I don't water the lawn in the Summer.

The BIG use I had planned for this was in cutting down on my brewing water use. My plate chiller uses a lot of water, usually 20 gallons or so to cool 5 gallons. Typically I either just drain this off, or use it to water plants if it's Summer. Today though, I used rain! And it worked pretty well, I got a good cooldown to 66. Perfect for ales! Unfortunately, of course I was brewing a lager... Best part though, I just poured the used water back into the barrel. This cut my total brewing water use down by at least half.

Of course, the City charges me about $3.80 for 100 cu. ft. of water (over 700 gallons) so in terms of savings...yeah I saved 11 cents. Wooo! But it's about Green building, and the DIY gratification I guess. My part of the city is under a major stormwater reclamation project right now, as each of those 11,000 gallons would otherwise drain into Shilshole Bay. And once I start watering the garden more often the gallons will start piling up.

Unfortunately the flow from the barrel is pretty slow. I blame drag from the long hose I have attached to the barrel, I'll try a shorter one and see if that changes anything. No way I'll be spraying anything with water pressure from the barrel, but if I get a watering can and maybe a soaker hose I should be set.