Since I'm installing a low pressure (25lb) micro-irrigation system outside to water hanging plants, I'm thinking that I could integrate an outdoor garden faucet into the system for summer use, about 20 feet away from the house on a wooden retaining wall (that runs between the house and garage).

At present I have a brass manifold with 4 garden hose outlets attached to a frost resistant sill cock on the exterior of our house. I'm using two of the 4 outlets to supply the micro-irrigation system using Orbit fittings and one of the outlets for a garden hose. So that leaves one garden hose outlet open on the brass manifold.

My question is simply whether I can use the remaining garden hose outlet to connect (with appropriate fittings) to a horizontal run of flexible 1/2" CSA rated (150lb pressure rated) polyethylene plastic pipe that in turn connects (with appropriate fittings) to a faucet mounted on the wooden retaining wall (with a drain outlet for fall use). I thought I'd run the 20' length of PE pipe about 12" horizontal above grade level and use a push-fit elbow to go up to the faucet mounted on the retaining wall. An existing concrete patio between the house and garage precludes running any underground pipe (without a whole pile of extra work).

Helpful suggestions most appreciated, including comments on feasibility, better alternatives and best kind of fittings to use with the 150lb 1/2" polyethylene pipe. Given a northern climate, I'd drain the PE pipe each fall. Thanks in advance!