Rainwater storage question

[Bronson]

Last year I bought and installed a 500 gallon water tank under the downspout on My 30 x 40 steel shop roof. With our lakes drying up,and the continuing drought, I am trying to conserve water, and use this system to water My back yard trees and shrubs. yesterday, I pulled the hose over to a sapling and turned it on. It is gravity flow only and not a lot of GPM. So, a Buddy came by and We got to visiting, and I forgot about the water. I dumped all 500 gallons on that one sapling. Anbody have any ideas on a easy way to put a timer, or limiting device on this system? I would like it to deliver 10 or 15 gallons max to each tree, if possible. Thanks!

 

[RedAggie03]

I'm using one of these Orbit timers with a lot of success.

http://www.amazon.com/dp/B004INGS8S/?tag=atomicindus08-20

I also added a y before the timer so I could still turn another hose on and off. I used it with soaker hoses.

 

[rlitman]

Not that this is helpful, but gravity flow won't provide enough pressure to activate sprinkler valves. It's probably enough to use with some sort of drip irrigation though (although the flow rates will be really low). You could probably run small lines around your trees and shrubs, and use "flag" emitters to drip water where you want it. Then you open the valve, and everything gets watered at the same time. Since it will drip so slowly, there's no runoff and waste, and it might take a day to empty the tank.

Just be sure to use a filter on the line, because any sediment will clog the emitters.

Don't bother with "PC" (pressure compensating) emitters, micro-sprinklers, or drip line, they'll probably do nothing at such a low pressure.