Collect the rain and water your garden for free
A water butt fitted to a downpipe captures hundreds of litres of free, soft rainwater off your roof — exactly what your plants prefer, and ready for the dry spell when you need it most.
Every time it rains, hundreds of litres run off your roof, down the drain and away — while a few dry weeks later you’re standing there with a hose, paying for treated mains water to keep the garden alive. A water butt simply closes that gap: it banks the downpour so it’s waiting for the drought. Even a modest roof area sheds a remarkable volume in a single shower, enough to keep beds and pots going through a dry spell.
Rainwater is also genuinely better for plants than tap water. It’s soft and free of the lime and chlorine in mains supply, which is why ericaceous plants like blueberries, rhododendrons and camellias visibly prefer it. And there’s a wider point in a warming climate: summers across Europe are bringing longer dry spells and tighter hosepipe restrictions, so storing your own water is becoming less a nicety than sensible resilience.
The one honest caveat is hygiene. Roof run-off picks up bird droppings and the odd bit of grit, so it’s perfect for established plants, lawns and ornamentals but not ideal for tender seedlings or salad you’ll eat raw — use the tap for those. Keep the butt lidded and the water turning over and it stays clean, sweet and ready for the next dry week.
How to do it
- Choose a butt to suit the space — a slim wall-mounted one for a narrow yard, a 200-litre-plus barrel where there's room — and stand it on bricks or a stand so a watering can fits under the tap.
- Position it under a downpipe from the roof or a shed, ideally close to the beds you water most so you're not lugging cans far.
- Fit a rain diverter into the downpipe: it feeds water into the butt and automatically sends the overflow back down the pipe once it's full.
- Add the tap and a lid — the lid keeps out leaves, algae and mosquitoes and stops small animals falling in.
- Link a second butt with a connector kit if one fills fast; a decent roof can fill a butt surprisingly quickly in a downpour.
- Use the stored water on beds, pots and the lawn, and save the tap for the kitchen — rainwater is soft and lime-free, which acid-loving plants especially like.
Pro tips & pitfalls
- Keep the lid on and the water moving; a sealed, shaded butt that you use regularly won't turn green or breed mosquitoes the way a stagnant open barrel will.
- Don't store rainwater for edible seedlings or salad leaves you eat raw — roof run-off can carry bird droppings, so use tap water there and save the butt for established plants and lawns.
What it's good for
Good for the planet
- Saves water A single butt stores a couple of hundred litres of rainfall, so a typical garden's summer watering comes off the roof instead of the mains.
Good for you
- Saves money Free roof water replaces metered tap water through the thirsty months, trimming a summer water bill — and there's no cost once the butt is fitted.
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