Installing the pipe and faucet
If dragging hoses around is a constant activity in your yard, install a remote faucet and eliminate that hassle forever. The job will take you a day or two (depending on how much trenching is required) and cost less than $100. Everything you’ll need is available at home centers.
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.
Call 811 a few days before you dig so the utility companies can locate buried pipes and cables in your yard. You only have to bury the water line about 6 in. deep. If you’re trenching in hard clay or rocky soil, that’s about as deep as you’ll want to go. If you’re working in soft soil, it’s smart to go at least 12 in. deep to reduce the risk of future damage. At any depth, you can easily protect the water line from shovel attacks: Cover the tubing with a couple of inches of soil, then pour in about 2 in. of dry concrete mix before backfilling the trench. Soil moisture will harden the concrete.
Copper pipe is best for the exposed plumbing at the house, but PEX tubing is best for 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 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.
The blow-out system
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-air line.
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.
The post and faucet
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.