Enough that the mechanism works, which for a rotating head is well above what a barrel gives. The number the maker used to obtain its coverage figure is the one that matters, and most listings omit it.
What each type needs
Soaker and porous hose. The lowest requirement on this shelf. Works on gravity from a butt, and over-pressurising it simply makes it leak at the fittings.
Drip emitters. Low, with a working range. Pressure-compensating emitters hold their rate across a range; plain ones deliver more near the tap than at the end of a run.
Oscillating sprinklers. Need real pressure to project a fan across the full width. Under-pressurised they water a narrow strip close to the unit and nothing at the ends.
Rotating and impulse sprinklers. The mechanism is driven by the water itself. Below its working pressure the head does not rotate — it points at one spot and dribbles, which looks like a broken sprinkler and is not.
Where the pressure goes
Hose length. Every metre costs a little, and thirty metres costs a lot.
Hose bore. The largest factor after the supply itself. A 13 mm hose and a 19 mm hose over the same distance deliver very different pressure at the far end.
Connectors. Every quick coupling is a restriction, and a cheap moulded one is a bigger restriction than a brass one. Four of them in a run add up.
Height. A garden that rises costs roughly a tenth of a bar for every metre.
Other draw. Anything else on the same supply while the sprinkler runs.
The check worth doing
Measure the time to fill a bucket of known volume from the tap, with the hose you actually use, at the end where the sprinkler goes. That gives you the flow you really have, which is more useful than any pressure figure — and it is the number that explains a disappointing sprinkler.
How this site handles it
Sprinkler pages here print the coverage figure together with the pressure the maker states it at, and say explicitly when no pressure is stated — on this shelf that is the majority. Hose pages print bore and stated working pressure, which are the two figures that decide what arrives.
Wherever this page and the maker’s own documentation disagree, the documentation wins. Every cutting width, cutting height, stated area, pack capacity, flow rate, head, sound level and application rate on this page comes from the maker’s own published figures, with the unit as printed and the source named. None of it is measured here, and no figure is converted into another convention, because a converted number is a different number. And the operating point this page always states: a pump’s flow figure is measured at zero head and its head figure at zero flow. Neither point is anywhere near where a garden hose runs, and the two cannot happen at once. This page reports both with the convention named, and reports a sprinkler’s coverage with the pressure it was obtained at — or with the fact that none was stated.
The questions that keep coming in
My sprinkler covers half what the box claims. Why?
Almost always pressure at the head rather than the head itself. Length of hose, bore of hose, a narrow connector and anything else running on the same supply all take their share before the water arrives.
Can two sprinklers run at once?
On mains pressure with a short, wide hose, sometimes. Each one takes flow, and flow lost is pressure lost at both. The symptom is two sprinklers each covering less than one would.
Last reviewed 26 September 2026