What is rainwater harvesting?
Rainwater harvesting is the collection of rainwater directly from the surface(s) it falls on. This water would otherwise have gone directly into the drainage system or been lost through evaporation and transpiration. Once collected and stored it can be used for non-potable purposes. These include toilet flushing, garden watering and clothes washing using a washing machine.
Why consider a rainwater harvesting system?
Despite the common perception that it rains a lot in England and Wales, our water resources are under pressure. A high volume of water is taken from the environment for human use. Demand for water is rising because the population is increasing, lifestyles are changing and the impacts of a changing climate are becoming more clear. In the south east of England, where larger numbers of people live and work, water is more scarce than anywhere else in England and Wales. In fact, there is less water available per person in this region than in many Mediterranean countries.
What are the benefits of a rainwater harvesting system?
- Rainwater harvesting systems can reduce demand for mains water and relieve pressure on available supplies. For customers with meters, water bills will be reduced.
- Reducing the volume of mains water supplied means less water is taken from lakes, rivers and aquifers and more is left to benefit ecosystems and help sustain the water environment.
- Rainwater harvesting systems can also reduce the risk of flooding and pollution as less rainwater is discharged to drains and sewers and, ultimately, to rivers. They can contribute to slowing down the flow of water and reduce the pressure on drainage systems in times of high flow.
The Code for Sustainable Homes - what's it all about?
- The Code for Sustainable Homes was launched in April 2007. The UK government made it mandatory for new build housing in England to be rated against the Code from 1st May 2008. This represents one of the most fundamental changes affecting house building since building regulations were introduced.
- The Code has been developed by the Building Research Establishment (BRE), Construction Industry Research and Information Association (CIRIA) and the Department of Communities and Local Government (DCLG).
- This Code replaced EcoHomes (for new-build in England) from April 10th 2007. The Code for sustainable homes assess nine major areas of development:
- Energy, water, materials, surface water run-off, waste, pollution, health and well being, management and ecology
SUR 1, WAT 1, WAT 2 - what's it all about?
Reducing the consumption of water in order to conserve stocks is fast becoming a high priority for specifiers, builders, contractors, architects and end users in order to achieve the ratings set out by the Code of Sustainable Homes and BREEAM.
By 2016 all new homes must comply with level 6 and in order to achieve this rating mains water consumption must be reduced from an average of 150 litres per person per day to 80 litres code level 5 and 6.
|Levels 1 and 2
||< 120 litres/person/day
|< 110 litres/person/day
|Levels 3 and 4
||< 105 litres/person/day
|< 90 litres/person/day
|Levels 5 and 6
||< 80 litres/person/day
Sustainable drainage systems (SUDS) often incorporate rainwater harvesting. SUDS reduce the risk of flooding by increasing the retention and control of surface/storm water. In England, Planning Policy Statement 25 "Development and Flood Risk" (PPS25)2 requires flood risk to be considered at all stages of the planning process to reduce future loss of life and damage to property from flooding.
PPS25 download (PDF, 426kb)
Credits for water use and SUDS
||Percentage of overall points
||Indoor water use
||External water use
||Management of surface water run-off from development
Aim of WAT 1 and WAT 2
To reduce all aspects of consumption of potable water throughout the home through the use of various water efficient appliances, fittings and recycling systems such as a rainwater harvesting system.
Aim of SUR 1
To design surface water drainage for housing developments which avoid, reduce and delay the discharge of rainfall run-off to public sewers and watercourses using SUDS techniques. This will protect receiving waters from pollution and minimise the risk of flooding and other environmental damage in watercourses.