As gardeners, we know that water is the lifeblood of our plots. But the tap water we often reach for isn't always the best choice for our plants. Rainwater butts offer a simple, sustainable solution that benefits both your garden and the wider environment. By capturing rain from your roof, you can save mains water, reduce your bills if you're on a meter, and give your plants a drink they'll truly thrive on.

Why rainwater is a gift for your plants

Tap water in the UK is treated with chlorine and, in many areas, contains fluoride and high levels of calcium and magnesium, making it hard. Rainwater is naturally soft, free from these additives, and has a slightly acidic pH that suits ericaceous plants such as camellias, rhododendrons, blueberries and pieris. It's also at ambient temperature, so it won't shock delicate roots on a hot day. For wildlife-friendly gardening, using rainwater reduces the energy and chemicals needed to treat and pump mains water, and it helps keep your garden resilient during hosepipe bans.

Setting up your water butt and diverter

A water butt is only as good as its installation. Choose a size that matches your roof area and garden needs—100 to 250 litres is typical for a small garden, but you can link several butts together for more storage. Position it on a level, stable base close to a downpipe. A stand raises the tap, making it easy to fill a watering can.

• Fit a diverter: This clever device fits into your downpipe and redirects water into the butt. When the butt is full, the diverter sends the excess down the drain as normal. You'll need to cut a section out of the downpipe, so check the instructions carefully.
• Ensure overflow: Connect an overflow pipe to a drain, soakaway or rain garden so excess water doesn't flood your patio or foundations.
• Add a tap: A simple tap at the bottom lets you fill a can or attach a hose. For gravity-fed irrigation, raise the butt higher.

Keeping your butt clean, covered and safe

An open water butt quickly becomes a breeding ground for mosquitoes and algae, and a hazard for curious wildlife. Always keep it covered with a tight-fitting lid or fine mesh. This stops leaves and debris from rotting, keeps the water clear, and prevents small animals from falling in. If you have an open top, add a ramp or floating platform so any creature that does fall in can climb out.

Clean your butt once a year, ideally in spring. Drain it, scrub the inside with a stiff brush and a diluted vinegar solution, then rinse well. Avoid bleach or other chemicals, as these can harm your plants and soil life. Check the diverter and overflow for blockages, and make sure the tap doesn't drip.

Putting rainwater to work in the garden

Rainwater is perfect for pots, hanging baskets and containers, where tap water can gradually raise soil pH and leave unsightly lime deposits on leaves. Use a watering can with a rose for a gentle flow that doesn't displace compost. For beds and borders, water directly around the base of plants rather than over the foliage—this reduces evaporation and helps prevent fungal diseases. Early morning or evening is best, when the soil is cooler.

Acid-loving plants will reward you with lush growth and better flowers. Seedlings and ferns also appreciate the softness. You can even use rainwater to top up ponds, as it's free from chlorine and closer to the natural water your pond life expects. Just make sure the butt is covered so you don't accidentally introduce mosquito larvae.

Rainwater harvesting as part of sustainable living

Using a water butt is a small change that adds up. It cuts your demand on mains water, which saves energy and reduces pressure on rivers and reservoirs. If you're on a water meter, it saves money too. In winter, when plants need less water, keep the butt connected so it captures rain for spring. You can also link your overflow to a rain garden or bog area, creating a wildlife-friendly habitat that soaks up excess water.

Combine your butt with other sustainable habits: mulch beds to lock in moisture, water less often but more deeply, and plant drought-tolerant species. A water butt is not just a practical tool—it's a statement that you're gardening with nature, not against it. So next time it rains, smile. Your garden is about to get a free, healthy drink.