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Starting Member


Monday, July 7th 2008, 1:58pm

Sytem off of hose bib...yes or no

Just getting ready to design a system for an older home. There are hose bibs in the same location that I would like to set up each sytem. Is it a good idea/possible to run directly off of the hose bibs or does the main have to be tapped into??


all wet

Active Member


Monday, July 7th 2008, 3:12pm

Bad idea. Too much pressure loss because of plumbing "detours" through the home not to mention volume issues due to corrosion inside the old pipe causing volume problems.


Advanced Member

Posts: 88

Location: Seattle Area


Monday, July 7th 2008, 8:21pm

Also, may be noisy with early AM watering, and water noise rushing thru household plumbing. If you are compteplating low volume irrigation (drip), hose bib sources are most usually adequate. I assume you are plnning to use this system for lawn, and usually higher volumes are needed than are located at typical hosebibs. Good Luck, Jeff


Supreme Member


Tuesday, July 8th 2008, 8:54am

While it's not impossible to use a hose bibb as a source, there are several issues.

As others have pointed out, noise can be a big issue. Many older homes have copper pipes and it seems like when ever water is running anywhere in the system, you can hear it. Add that to the fact that it's generally suggested to irrigate early in the morning and it can be a pure nusance.

There's also the issue of constant pressure. If you want to connect with the hose bibb (as opposed to tie into the pipe leading to the hose bibb), you'll have an issue with the fact that washers used to connect a hose to a hose bibb are not designed for constant pressure (because to be able to run automatic valves, you'd have to keep the hose bibb open all the time).

Pressure has also been pointed out as a possible issue. You will have pressure losses with the pipes detouring into the house compared to what you can get just tapping in at the meter. There is also the issue of pressure regulators. Many homes have pressure regulators to insure the water pressure in the hose doesn't exceed about 50psi. Additionally, most homes are build with two hose bibbs, one located before the regulator, and one after. If you tie into a hose bibb, you may be tying in after a pressure regulator.

You have to also keep in mind that even if you tie into a hose bibb, you still need to have a proper backflow preventer.

So the bottom line winds up being a question of how much pressure (and flow volume) you can expect to get from the hose bibb and how much area you need to water, and how many zones do you want to deal with. It's not impossible, but depending upon other factors, you'll likely find it more practical to tie into the main line. (Obvious exception is a drip irrigation system using a drip irrigation kit designed to be attached to a hose bibb for the season).

To get started, you need to 1st find out about what sort of backflow requirements your local plumbing codes require. After that, you need to determine what is your static water pressure (check at multiple hose bibbs to ensure you find the pressure before any regulator). You'll then need to get an estimate of the volume your system can produce. While it has lots of flaws, you can start with the basic bucket test. You'll likely find your volume from a hose bibb to be less than 5gpm (low number for typical irrigation needs).

But as an example of where your situation could REQUIRE you tie into the main line would be if your hose bibb is after a pressure regulator and local codes require an RPZ backflow preventer. That would mean your system would basically START with only 35psi at best (and that's before pressure losses for the valves). If you're wanting to design a system using rotors, that just won't be enough pressure.

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