Rainwater Harvesting at Home: Reduce Your Water Bills by 50%
Collecting rainwater for garden use is one of the simplest and most effective eco upgrades for any home. Here's a complete guide from basic water butt to full garden system.
Why Harvest Rainwater?
Treated mains water used for garden irrigation is both environmentally costly (treating and pumping water uses significant energy) and financially unnecessary — plants actually prefer rainwater, which is naturally soft and free of the fluoride and chlorine present in tap water. A 5000-litre garden needs roughly 1000–2000 litres of water in a dry summer. Collecting and using rainwater can reduce mains water bills by 30–50% in summer.
The Basic Water Butt
A 200-litre water butt connected to a downpipe with a diverter is the starting point. Installation is genuinely simple: fit a diverter kit to the existing downpipe (available at any garden centre for £10–15), position the butt on a raised stand (gives better flow from the tap), and connect the supplied overflow hose back to the drain. Total cost: £20–60, installed in under an hour.
Scaling Up
Multiple butts can be linked in series with a simple connector kit — doubling capacity without doubling cost. For larger gardens, an IBC (intermediate bulk container, 1000-litre) can be repurposed as a garden water tank, bought secondhand for £20–50. Partially bury it (reduces evaporation and algae growth) and attach a tap at the base.
Underground Tanks
For serious water harvesting, an underground tank (1500–10000 litres) with a submersible pump can supply automated irrigation. Installation typically costs £800–3000 depending on tank size and pump quality — but this effectively eliminates garden water bills entirely and supplies water through the longest dry periods.
Keeping Water Butt Water Safe
Water butt water is not safe for drinking but is excellent for all garden use. Keep the lid on (reduces algae, prevents evaporation, stops mosquito breeding). Use the water regularly — stagnant water deteriorates. Add a piece of copper pipe or a copper coin — it has mild antibacterial properties and can extend water quality.