Rainwater can be collected from the roofs of homes, garages, greenhouses and other garden structures as long as they have gutters and a down pipe that enters the drain at ground level. If all of your rainwater goes to a soakaway rather than the foul sewer you may be entitled to a discount from your water company.
Water butts with rain water diverters are designed to collect water from the down pipe and still let the overflow enter the drain.
Aim to clean water butts annually to prevent plant diseases spreading. Collected water can be used on established plants rather than seedlings, because of the risk of fungal plant diseases. If multiple butts are used, rotate the use of each one to keep stores fresh. They can be joined together by either a water butt connector kit or a siphon.
Local councils and DIY stores are good places to purchase basic plastic water butts. It is easier to access the water if the butt has a tap at the base and sits on a stand, so that the watering can will stand on the ground under the tap. Stands can be either ready-made or improvised with a pile of bricks, but it’s important to make the base firm and level in case it topples, and use the lid supplied to stop wildlife falling in, prevent algal growth and discourage mosquitoes. More expensive butts moulded to look like beehives or terracotta urns are an attractive option, as are recycled wooden barrels. Slimline models are available for narrow spaces.
Climatic change projections suggest an increasing proportion of rain will fall in winter, so it may become cost effective to build in rainwater storage when constructing new homes. This usually involves sinking a large tank somewhere in the garden, pumping water out for use in the garden or for domestic tasks such as flushing toilets.
The UK Rainwater Management Association can advise on purchase and installation of rainwater harvesting systems.