PEX Tubing PEX tubing, which is flexible and more resistant to damage from freezing, is the best choice for the supply line to the faucet.
The inside connection To get the best flow rate at the garden, tap into an interior 3/4-in. cold water line. If you can’t find one that’s convenient, tap into a 1/2-in. line instead (you’ll just get a slightly lower flow rate). If you have a water softener, tap into a water line before the softener.
Copper pipe is best for the exposed plumbing at the house, but PEX tubing is best for the underground. It’s a lot cheaper than copper and it’s easier to install than CPVC plastic. With PEX, you can make a continuous run from your house and can make turns without installing a single fitting. Plus, PEX tolerates mild freezing better than either CPVC or copper (in case you’re late blowing out the line). However, you’ll have to invest in a 3/4-in. PEX crimping tool. If you don’t want to shell out the cash, use CPVC.
To attach PEX to a copper line, solder on a transition fitting, then crimp the PEX to the fitting with a crimping tool.
If you live in a freeze zone, you’ll have to blow out the system before the first hard freeze. It’s easy to do with a home air compressor, but you’ll have to install the components now (instead of during a snowstorm).
At the house, splice in a tee and a threaded female 3/4-in. adapter, and cap it with a plug. That’s where you’ll connect your compressed airline.
At the garden, install a blow-out valve (a ball valve is best) below grade in a gravel pit. Use a sprinkler system valve box to cover it. Before the first freeze, close the shutoff valve and unscrew the plug. Next, screw in a standard air hose fitting and a reducer and connect your air hose. Out at the faucet, open both the faucet and the blow-out valve and let the water drain. Then, close just the faucet and blow out any remaining water with your compressor. Finally, close the blow-out valve and replug the blow-out fitting back at the house.
We cut a length of hollow PVC fence post to mount the faucet, but you can build your own post out of any material. Make sure the PEX runs inside it to protect it from sunlight—UV rays reduce its life. Set the post at least 18 in. deep. Screw the sill cock flange to the post and install a screw-on backflow preventer.
Note: Check with your local plumbing inspector for backflow prevention requirements in your area.
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