Rainwater Harvesting

Rainwater harvesting is simply the collection of rain which fall onto roofs, then stores it in a tank until required for use. When required, the water is then pumped to the point of use, thus displacing the demand for mains-water.

In the process, a volume of water is kept out of the storm-water management system, thereby helping to reduce flooding risks.


Rainwater harvesting systems summary

Rainwater is captured from the roof, and delivered, via guttering and down-pipes, to a storage tank, where it is filtered on entry. On demand, a submersible pump delivers the water to the property via a separate plumbing system that feeds toilets, washing machines, etc.  Potable water (drinking water) is kept separate.

The size of the storage tank is determined by the size and occupancy of the property and rainwater collection area of the property.


Considerations for fitting a rainwater collection system to an existing property

  • Modification to the existing rainwater drainage system to carry water to an agreed collection point
  • Access for the tank and excavation is required.
  • Separate Internal plumbing is usually required to separate out the drinking water from the non-drinking water (WC, washing machine & outside tap).


Benefits for rainwater harvesting

  • Rainwater harvesting reduces mains water usage.
  • Reduction in costs where charges are made for water usage
  • For remote areas provides a suitable off mains supply
  • It can form part of a water management scheme, by controlling the flow-rate off site.
  • Planning departments are looking more favourable towards rainwater harvesting.

Types of Rainwater harvesting systems

  • Domestic and Commercial systems
  • Garden/irrigation systems

With a rainwater harvesting system, a typical household can expect to save around 50% of their mains water needs.

The inclusion of a rainwater system can help with water related issues during the planning process. And, in more remote areas, rainwater can be upgraded to fully drinkable standard. 




© 2009 Argyll & Bute Environmental