RLB_UK_Riders_Digest_2013

Rainwater Harvesting
What is it?
There are two uses of harvested
rainwater, potable and non potable.
Non potable supplies can be as
simple as a drain pipe into a water
butt. A potable system involves
much greater planning and system
costs due to the possibility of
contamination. Systems uses can
provide toilet flushing and irrigation,
washing machines can be supplied,
but may lead to problems involving
odour and discolouration.
Savings rely on the need for non potable supply. The UK has
an abundance of water and this keeps our mains supply costs
relatively low. This however appears to be changing with the
UK’s first drought orders and recent hose pipe bans in the
South East, prices will surely begin to rise.
How does it work?
Rainwater is collected rather than discarded, reclaimed water
can be used for several applications such as toilet flushing,
irrigation, washing machines and car washing
Indirect pumped systems collect rainwater in a tank and
then pump it to a high level header tank which provides a
head of water to gravity feed the outlets
Direct pumped systems which feed the outlets without the
need for a header tank
The use of rainwater for toilet flushing and other non potable
uses reduces the consumption of treated mains water
Saves water supply costs
Can help to reduce surface water run-off and risk of flooding
Limitations
Requires water filtration and treatment
Roof materials may effect the quality of harvested water
Cleaning should be regular and debris removed to prevent
water contamination
Installation and maintenance costs may not justify savings
Pumps, filters and sensors require regular management and
maintenance
Providing sufficient water storage capacity may present a
problem
CO2 saving Low
© Rider Levett Bucknall UK 2013 103