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jbk 09-29-2009 01:57 AM

Do I Need a Backflow Valve for Hose-Sprinkler?
We're re-landscaping a 40' x 40' backyard in San Diego that was totally neglected by the previous owner. We'd like to put in a small (20' x 30') lawn area for our kids, a play area with a swing and a sandbox, and two rows of vegetable garden, and plant shrubs and ground cover for the remaining areas. We can't afford an in-ground sprinkler system, so I was going to just attach one of these faucet manifolds ...
... to our backyard exterior faucet, and make an above-ground sprinkler system with 3 different zones. Each of the 3 zones would be fed by a garden hose with a battery-operated timer. One of the 3 would be a sprinkler for the lawn. A second would be for the vegetable garden, and the third for a drip hose for the shrubs and ground cover. The 4th valve would be for a garden hose for manual hose use.

My question is, do I need to attach a back-flow preventer valve in my set-up? If so, can I attach one just at the top of the manifold? Or do I need one for each of the 3 manifold outlet valves connected to a sprinker or drip hose? Is there one you recommend?

Also, do you see any problems with what I'm planning to do?


Kap 09-29-2009 03:25 AM

Considering you can get one for under ten bucks, I would use one.

user1007 09-29-2009 02:21 PM

Do consider installing a drip system for everything but the lawn. With a drip system you will be watering in outputs of gallons per hour (GPH) and not gallons per minute (GPM) and the water will only be discharged where you want it. You will save enough in short order to pay for it.

downunder 09-29-2009 06:20 PM

If you are using this strictly for an irrigation system, there is really no need to have a backflow preventer. Their purpose is to prevent anything from siphoning back into the water system in the event something like a water line was broken somewhere along the system, creating a vacuum of sorts from your house into the local water supply. So, if you were using a hose to apply fertilizers and/or herbicides you might want to consider having one.

First, I would check with my local water authority. Most places nowadays require a backflow preventer at the meter (on your side). So the question here may be moot.

If you do decide to install one at the faucet, just one at the faucet going into the manifold will suffice and will protect all connections downstream. But I can agree with Kap, if in doubt spend the ten bucks.

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