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View Full Version : Gravity Fed Garden Hose - How High Should The Water Tower Be?



bhoen
06-13-2011, 03:28 AM
this is a very novice question I suspect

I am helping install a 120' x 60' garden at my local k-5 school at a site where they do not currently have water. We were planning on building a water platform where a 500 gallon tank would sit which would feed water through a hose for the garden to use. (The tank would be filled via rain water collected on the roof above it and via pump as needed. Long term we will connect to the schools water.)

Assuming we will have a run of hose no longer than 100', could we get away with having the water tank on a 6' platform?

I assume the biggest question is how slow will the water run out of a hose like the one I envision. Given the set up, any idea how long it will take me to fill a gallon bucket? What sort of pressure to you need to have a hose sprayer work? Will the system generate that kind of pressure?

Thanks for any advise you have. Frankly I do not know where to start with this one.

Ben

LLigetfa
06-13-2011, 04:55 AM
Rounding off, 25 feet will give you about 15 PSI so working on multiples of that, 75 feet would do it.

Edit... OK, I was a little off... each foot of rise equals about .43 PSI so 25 feet would be closer to 11 PSI.

johnjh2o1
06-13-2011, 05:00 AM
You will get .43 PSI per foot of rise. At 6' that will give you a little over 2.5 PSI

John

TJanak
06-13-2011, 06:45 AM
Gravity feeding from a cistern is more about volume than pressure. At the minimum I would use a 3/4" hose because they come with regular hose connections on the ends. But ideally I would go with 1" or larger.

To operate a sprayer I would think you need at least 15 psi.

hj
06-13-2011, 07:09 AM
Your limitations mean you cannot have a "sprayer system". Use drip heads or a soaker hose which is less pressure dependent.

Gary Swart
06-13-2011, 12:52 PM
Seems to me you are going to a lot of work for nothing. You say you're going to connect to the school's water to supplement the rainwater, so you will have to trench and lay pipe anyway, so why not install a backflow preventer at the connection to the school, run PVC pipe to the garden area and do the whole job without messing with a cistern or storage tank at all?

jimbo
06-13-2011, 07:46 PM
You will need a pretty impressive platform to get 500 gallons of water 20 to 30 feet in the air!1

hj
06-14-2011, 05:50 AM
quote; 500 gallons of water 20 to 30 feet in the air!

And a tall building to have the water run off the roof into the tank.