Garden Spigots

Garden spigots are outdoor taps set around the growing ground, fed from stored water by gravity alone. They shorten the walk: filling a can or running a hose happens beside the bed rather than back at the tank. They move water the store already holds and make none of their own, which matters because a tap looks like a source and is not one.

What the network can do is decided by head, meaning the height of the water above the tap. Every 3 m (10 ft) of fall is worth about 5 psi of pressure, roughly half a psi per foot of drop below the tank outlet. Ordinary drip irrigation is built for 20 to 30 psi and even low-pressure kit wants 15 to 20, which would need some 12 m (40 ft) of fall between tank and emitters - more than most sites have. Hence taps, not drip. What a few feet of head does well is fill a can, run a hose at a trickle, flood a basin and feed a soaker line; the layout is built around those.

Water stored off a roof is untested and is not drinking water, and the guidance is to keep it off the edible part of any plant - leaves, fruit, roots, herbs. The exception is watering that never touches what is eaten: at the base of fruit trees, tall berry bushes and trellised crops such as tomatoes, melons and cucumbers. That decides where the taps belong, and why they cannot replace a tested supply across a whole garden. Every outlet needs marking plainly as not for drinking, because an ordinary-looking tap is something a visitor will fill a bottle at. Where such a line ever meets a drinking supply, a backflow preventer or an air gap has to separate them, since a hose left lying in a trough can draw water backwards. Lines and taps left full through a hard freeze split, so the network is drained first. The rest is clearing the outlet screen, since low pressure cannot push debris through a fitting, and watching for weeping at joints, as a leak at half a psi never sprays.