A quick guide to: harvesting rainwater

Capturing rainwater for use in your business can be a simple way of saving money and conserving natural resources. We look at how it’s done, what it costs and some issues to consider.

Why harvest rainwater?

  • It’s sustainable, easy and cheap
  • It may reduce the risk of flooding when used as part of a sustainable urban drainage strategy
  • It helps avoid water shortages
  • It can save you money

Storing rainwater for future use requires little more than a large tank or container and a method of directing rainwater from your roof into it, usually via gutters and pipework. The water is filtered, then pumps are used to move it to where it’s needed. The amount you can harvest depends on how large your roof area is and, of course, the weather.

Commercial rainwater harvesting

With water demand increasing and costs rising, many UK businesses are adopting rainwater harvesting systems to help manage the variable costs of water supply. Water independence also improves a company’s sustainability credentials.
A commercial system can have very short payback periods, making it a cost-effective solution for many offices and industrial buildings.

Rainwater harvesting for agriculture

The farming sector is a heavy consumer of water, but it also already routinely collects and uses rainwater to supplement the mains supply.

The livestock industry, for instance, consumes huge volumes of water, predominantly for cleaning and drinking. More than 100 litres can be used per animal per day, according to past figures from the Environment Agency.

Rainwater harvesting enables producers to collect ‘free’ water, and with new and improved technologies in filtration, pumping and storage, systems are easy to use and maintain.

Rainwater Harvesting: an on-farm guide (Environment Agency, 2009) says that “in addition to using water more wisely, rainwater harvesting is a way of reducing your reliance on mains water, or on your borehole or spring. Making use of the rain that falls on your farm buildings can save you money. 

Rainwater harvesting might not be suitable for everyone. But even if it cannot supply all your water needs it’s still worth thinking about. It can reduce your costs and help reduce your environmental impact.

Why should I start harvesting rainwater now?

Flood events are growing increasingly common in Britain, and the stark environmental and economic impacts are obvious. But measures to alleviate the damaging effects of flooding can have a counter-effect and create water shortages in dry periods.
There is already pressure on UK water supplies, says the Environment Agency, and this will worsen as the population grows and rainfall patterns change.
Harvesting rainwater can help reduce flooding as part of a larger drainage strategy, relieves pressure on water supplies and provides individuals and businesses with a more sustainable, cheap source of water.

Do I need a licence to harvest rainwater?

The short answer is no. No licence is required to collect, store, and use rainwater. However, you may need a water abstraction licence if you wish to combine harvested rainwater with ground or surface water from certain sources.

How much does a rainwater harvesting system cost?

According to the UK Rainwater Management Association, the cost of an average, fully functioning domestic system will be between £2,000 and £3,000, excluding the price of installation.

A commercial system for a small business can be around the same price as a domestic system, while the cost of a larger commercial system can rise to £10,000 or more. But if your business consumes a high volume of water, harvesting rainwater can provide a significant saving in a short period.

“It is important to consider all the costs, including both capital and maintenance costs, to determine the difference a rainwater harvesting system can make,” says the Environment Agency’s on-farm guide. “You will need to assess your current energy use for pumping water and compare it to the planned system.”

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