I have several medium-sized planters on the roof of my building that need to be watered when I'm away. I have access to a standard garden faucet, but there is a "walkway" of sorts between the faucet and my planters. Consequently, I've been told that I should limit myself to 1/4" tubing to water my plants. There are additional constraints: The faucet is in a locked-off area, meaning that I will need a solenoid-controlled valve to turn the water OFF and ON. However, the solenoid valve must be in close proximity to my planters to avoid running wires across the walkway. The building owner is rightly concerned about clutter and hazards on the maintenance walkway.

From previous experience, I've used Rainbird hardware. My first thought was to use their 1/4" tubing to connect the faucet to the emitters in my planters. T-junctions would be used to branch off to cover all the planters (5). A DC-powered solenoid valve would be used to turn the water on & off, and a small timer circuit would control the solenoid valve. Completing this system will also require identifying the necessary adapters to interface the solenoid valve with the 1/4" irrigation tubing. From my limited knowledge, this seems to be an NPT-to-barbed adapter of some sort?

Following is an outline of my current thinking on the layout, partly based on comments & answer already received, and some unresolved questions:

  1. 25 psi pressure regulator. I estimate the total run of tubing (from faucet to the first planter) at 50-60 feet. Will 25 psi yield enough flow for all of the planters?

  2. Faucet-to-1/4" Tube adapter... Please note that I'm not using drip tube, but the regular 1/4" distribution tubing.

  3. 12-or-24 Volt DC solenoid valve: This selection is proving a challenge as some of the valves get poor ratings, and others are quite expensive. Are there other alternatives?

  4. Fittings/adapters for NPT-to-1/4" distribution tubing. Most valves I've seen use 1/4" NPT, which is significantly larger than 1/4" distribution tubing. I know there are NPT-to-barbed adapters, but it's not clear to me whether these will work reliably with the 1/4" distribution tubing. Any experience or suggestions with this would be helpful.

  5. Series-or-parallel: I have 5 planters now. Should I use a series of T-junctions, or a manifold to distribute water?

All inputs are appreciated, and hopefully this will be the "final revision" to this question.

  • 1
    They make combo valve/timer assemblies that screw right on to the faucet and that feed a hose, which then can feed a soaker hose. Pressure isn't going to be a problem. The fitting you want is SKU #1000029939 from Home Depot, by the way. Apr 28, 2021 at 3:13
  • @TedMittelstaedt: That's very useful, thanks. The location of the faucet is such that I must run 1/4" tubing from the faucet to my planters (they won't allow garden hose for that run). Neither will I be allowed to run wiring into the area where the faucet is located. This means that the solenoid valve must be located near my planters, and ideally the valve inlet & outlet may will accept 1/4" tubing - or adapt to the 1/4" tubing. My apologies for failing to include these details in my original question. I under-estimated the "plumbing challenges" for this project!
    – Seamus
    Apr 28, 2021 at 5:46

1 Answer 1


Problem is the pipe from faucet to solenoid is mains pressure. The barb and ratchet clip style connection isn't rated for that pressure.

if you can run pvc pipe for that stretch then that would be much less likely to leak.

Effectively extending the mains from the faucet to a new outlet near the garden.

The consequences of a big leak, are they very bad?

  • 1
    Then add a pressure reducer to the drip runs. dripworks.com/drip-irrigation/pressure-regulators
    – DaveM
    Apr 28, 2021 at 12:41
  • Re the pressure rating: You may be correct, but McMaster-Carr sells some adapters rated at 150 psi?? The bldg owner wants "small" tubing - he's set against PVC in particular, perhaps due to some bad experiences/frozen pipes, etc? Leak consequences... well it is on a roof which gets rained on, so I'd say, "To a point, not particularly disastrous consequences."
    – Seamus
    Apr 28, 2021 at 23:00
  • The fitting may be rated for the pressure, but not the pipe and ratchet clip combination. Maybe if the stainless steel rings are used it would be safer (the ones that tighten using a screwdriver) May 8, 2021 at 11:08

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