Not too long ago my wife and I decided to get really serious about rainwater harvesting. For too long I’d been using a series of 32/60 gallon barrels and they would last a few weeks after every downpour in the monsoon season but as a year round solution they were not up to the job.
In Arizona there is actually a tax credit for RWH equipment I forget what percentage but it should help with the roughly $1300 we spent on all the components which are:
2 x 4 x 6.5ft tanks (galvanized culverts, capacity approximately 500 gal each, about $400+ ea.)
2 x 10ft x 3in sticks of ABS pipe
6 x 2ft lengths of 1in PVC pipe and assorted elbows
2 x Boiler pressure relief valves
ABS and PVC glue
1 gallon white latex hose paint
1 gallon Drylok concrete sealer
22 80lb bags of concrete
3 tubes of Cet Seal low VOC sealant and adhesive
Made to order flat cistern lids 50″ x 3″ (almost as much as the barrels themselves)
1000 gallons of rainwater !?
Well, that’s the idea. I missed monsoon season and there where a couple of occasions where the barrels where in and concreted, but not sealed, and where sitting in ankle deep water on the outside, but bone dry on the inside 🙂 it was quite ironic.
But yes, 1000 gallons of rainwater (probably more like 850+) right now one tank sits at about 1/4 full, as I capped the other one off because I still haven’t sealed it. Gosh I’m lazy.
I figured my current garden uses about 8 gallons of water during summer months, and I plan on having many more plants in the future (right now it’s about 14-16 in the ground and about 15 in pots) I think 12 gallons per day isn’t an extreme summer number and I should prepare for it.
900 gal / 12gpb = 75 days of water.
Of course that number depends on rainfall and how much I actually use, also not including the additional 60 gallon ish storage I have on other tanks hooked up. I can’t even imagine a scenario where we’d have no utility water; but it doesn’t mean I shouldn’t think about it. Potable water storage isn’t a bad idea in addition to plant water.
Drinking rainwater is a tricky business I haven’t fully looked into yet but I’m assuming that it involves lots of filtering, UV lights, possible some tablets and boiling; something else I should do before it’s actually necessary.
Rainwater harvesting saves!
Money. Time. Energy and of course WATER.
Water costs money, pumping it to your house takes time and energy, vast amounts in fact, one of the main energy users in Tucson is water pumping. And where does that energy come from ? a coal fired plant that is evaporating acre-feet of what substance in order to produce power ? WATER.
As you can see the water, energy and emissions savings are huge over the life of a rainwater system.
There are many things you can do before even considering a PV system for your home, solar hot water and rainwater harvesting are 2 of the simplest (beyond changing to CFL bulbs) and cheapest ways to conserve energy.
Enough talk, Pictures !
Setting up the pipes that are underneath the barrels. This is a bottom feed system, the feed pipe basically becomes your downspout, in this case a 3″ ABS pipe and will stay filled with water on the side of your house up to the level of the barrel.
I think bottom feed systems look better than top feed.
Moving the barrels is a pretty big task, they weigh about 180lbs a piece and some of the edges can be pretty sharp.
I welded up some 3/8″ rebar into handles and used load straps to secure them to the barrels, enabling 2 people to lift them vertically into place.
I poured concrete after the barrels where in place, I prefer this method to pouring a slab and then setting the barrels.
Even though this method is probably harder, I think you buy a lot less concrete and actually get a more secure footing as you can pour up to a desired measurement rather than having to push the barrel into the concrete.
I also placed some rebar stakes into the ground and bent them over for additional security in conjunction with several CMU blocks to displace some concrete, and a section of wire fencing laid in on top to help protect against cracking.
One major drawback to this method though is the spatter it creates. You can just paint over it, but I cleaned off most of it before I sealed the concrete, sealed the barrel seam and then painted over were the seam was.
Useful link: http://www.harvestingrainwater.com/ – Rainwater Harvesting for Drylands and Beyond by Brad Lancaster