Yes. The grass does not care — the constraints are how much you have and how hard it comes out.
Volume is the first constraint
A thorough watering is in the region of fifteen to twenty-five litres per square metre. A hundred square metres of lawn is therefore one to two thousand litres in a single application.
A domestic water butt holds a few hundred. Linked butts and a larger tank change the arithmetic, and for lawn irrigation specifically that is what it takes.
This is why rainwater on a lawn is realistically a supplement, or a supply for a small area, rather than the way a whole lawn gets watered through a dry month.
Pressure is the second
Gravity from a butt gives roughly a tenth of a bar per metre of height. That is enough for a can, enough for a soaker hose, and not enough for any rotating sprinkler. A pump is the answer, and pumps have their own shelf and their own page here.
What rainwater brings with it
Debris. Roof grit, moss, leaf fragments and insects. For a can or a soaker it is irrelevant. For a drip system it is the thing that ends it: emitters block, and a blocked line is invisible until the plants show it. A filter between the butt and the system is not optional.
Biological growth. A butt in sunlight grows algae, and a dark-walled, lidded butt does so far less. Some listings on this shelf make a point of the wall opacity for exactly this reason.
Sediment. Everything settles to the bottom, which is where most butt taps are. Drawing from slightly above the base, where the outlet allows, avoids stirring it.
What this site does not say
Whether rainwater is suitable for anything other than watering. It is not a drinking supply, and a rain barrel is not a potable source — nothing on the rain barrel shelf here is described as one.
How this site handles it
The rain barrel family prints capacity, material and whether a tap is included. The pump family prints flow and head with the conventions named. Between the two, the pages say plainly when a barrel alone will not drive a given watering method.
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
Is rainwater better for grass than tap water?
It is softer and free of the treatment residues in mains supply, which matters to some plants. Lawn grass is not fussy, and the practical difference on a lawn is not the reason to use it.
How big a butt do I need for a lawn?
Larger than intuition suggests. A single thorough watering of a modest lawn is hundreds of litres, and a typical domestic butt holds two or three hundred. For lawn irrigation a butt is a supplement, not a supply.
Last reviewed 26 September 2026