Rainwater Harvesting: Sustainability and Savings

While the UK generally enjoys higher rainfall than the global average, drier summers in recent years are threatening the long-term supply of water throughout the year. Add to this the steady rise in the cost of mains-supplied water, and rainwater harvesting becomes a practical and cost-effective answer.

Rainwater harvesting: what it is and why it’s important

Not all rainwater soaks immediately into the soil. Where it falls on roofs, driveways, roads and other non-porous surfaces, it is channelled into storm drains, soakaways or watercourses.

Rainwater harvesting interrupts this process by diverting rainwater into large aboveground or underground holding tanks. On its way to the tank, the rainwater is filtered to remove leaves and other debris so that the water in the tank is reasonably clean. Not clean enough to drink (although we cover that later), but certainly clean enough for many uses around the home or in industry and agriculture, where drinking-quality water supplied from the mains is not essential.

This reduces the demand for mains-supplied water, with obvious benefits.

1. Rainwater harvesting saves drinking-quality water for where it’s needed

With forecasts suggesting that we are likely to see hot, dry summers more frequently, we must use our water resources more carefully. By saving and storing rainwater during wet seasons, we reduce the likelihood of water shortages during the drier months.

1. Rainwater harvesting reduces household bills and business overheads

Rainwater harvesting system manufacturers estimate that they can save up to 50% on household water bills. Agriculture and some industries consume large volumes of water, so this cost can be reduced by harvesting rainwater.

What can harvested rainwater be used for?

There are many water uses around the house that don’t require potable (drinking-quality) water, including one of the largest uses of domestic water – flushing toilets – which can account for 25-30% of the average household’s water consumption. Other obvious domestic uses for harvested rainwater are watering the garden and washing the car, but it can also be used for washing machines.

Generally speaking, harvested rainwater isn’t suitable for drinking, although extra-fine filters that remove particles as small as 5 microns and ultraviolet sterilisers that kill microorganisms can be fitted to a rainwater harvesting system to make the water safe to drink or use for cooking. This filtration and sterilisation can also make harvested rainwater safe to use for baths and showers.

Industrial processes that use water for cleaning and cooling can often reduce mains consumption with a rainwater harvesting system, providing the process doesn’t require potable water.

Harvested rainwater can also be used for watering in agriculture, horticulture and nurseries, and to provide drinking water for livestock. As cattle and larger animals consume a lot of water, this can make significant savings. 

How much money can rainwater harvesting save me?

The amount of money you can save by using a rainwater harvesting system depends on the surface area you are collecting water from, the size of the system and the amount of water you use. After all, while a water butt is a form of rainwater harvesting it is unlikely to significantly reduce your water bills!

Proper rainwater harvesting systems use large capacity tanks that hold water in the thousands of litres. Providing you can capture and store sufficient rainwater to keep up with demand, you can expect to reduce your domestic water bills by around 45%. Naturally, this needs to be balanced by the purchase and installation costs of your system, plus the 5-10 pence per week running costs, but the bottom-line savings are likely to be enough for the system to quickly pay for itself. 

We hope you have found this information helpful and interesting. If you have any further questions you are always welcome to call our friendly team of experts on 01420 555600 or email [email protected].

Also, look out for more articles in our ongoing series of blog posts, bringing you useful information, insights, guides and tips on all things drainage!