Setting up a water butt for the garden
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A water butt collects rainwater from a roof downpipe for use on the garden. Even a 200-litre butt can save significant water during summer — useful for watering, washing the car, or cleaning paths.
Choose a downpipe from your house, garage, or shed near your vegetable patch or garden area. The butt must sit on a raised stand or paving slabs to allow a watering can to fit under the tap — most stands raise the butt 300–400mm.
Fit the diverter kit: cut the downpipe at the correct height using a hacksaw (the kit instructions specify the cut point). Insert the diverter — when it rains, flow is redirected into the butt; when the butt is full, overflow returns through the diverter back down the pipe.
Drill an overflow hole near the top of the butt and fit the overflow pipe — direct this away from the house foundations. Ensure the butt has a tight-fitting lid to prevent mosquito breeding and keep water clean.
Position the butt on level ground or a purpose-made stand. A full 200-litre butt weighs 200kg — ensure the base is solid and stable. Fit the tap supplied: typically a ¾-inch brass tap with a rubber washer.
In winter, drain the butt completely to prevent ice cracking the container. Disconnect the diverter so the full downpipe flow continues to the drain. Store the butt upside down or inside if possible.
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Frequently asked questions
How much water can I collect in a water butt?
A standard 200-litre water butt fills completely in moderate rainfall from a typical roof. In an average UK summer, a water butt can save 5,000–10,000 litres — roughly 100 watering-can fills. Multiple butts connected in series can collect significantly more.
Can I drink water from a water butt?
No — rainwater collected from roof surfaces contains bacteria, debris, and chemical contamination from roofing materials and bird droppings. It is suitable for watering plants, washing cars, and cleaning paths, but must not be used as drinking water or for food preparation without proper filtration and treatment.
Should I cover my water butt?
Yes — always fit a tight-fitting lid. An open water butt encourages mosquito breeding, allows debris in, and permits algae growth that blocks the tap. A lid also prevents evaporation and keeps collected water cleaner for longer.