• Conventional Block Paving
• Permeable Paving
• Sustainable Urban Drainage Systems
• Total Infiltration
• Partial Infiltration
• Non Infiltration or Tanked
• Permeable Sub-Base Replacement Systems
• Rainwater Harvesting
• Further Information
• New Government Legislation
• Pack Information

Rainwater harvesting is the collecting of rainwater from roofs and the underground tanked systems of permeable paving to use in or around buildings for non potable purposes such as watering the garden, car washing or toilet flushing. The run off water used for harvesting needs to be of reasonable quality and should be free of debris and sediments. Permeable paving systems will provide the filtration to achieve this.

The water can be stored in the permeable sub-base of a permeable paving system.

It is however very important to note that the storage volume for re-use is normally separate to that for rainfall attenuation. This is because the two types of storage have different requirements.

• Rainwater re-use - must be full for as much of the time as possible so that water is available for use.
• Stormwater attenuation - must be empty most of the time so that it can temporarily store water from rainfall events.

Rainwater Harvesting systems will usually have an overflow or pipe outlet to a soak away or to the urban drainage system. The outlet principles for Non-Infiltration/Tanked systems shall apply. Rainwater Harvesting will not only reduce rainwater run off into the drainage system but will also reduce the amount of mains water used. This contributes to water efficiency and provides savings on water bills if using metered water.

Advice is available from the UK Rainwater Harvesting Association - www.ukrha.org