Phase 1 Footings & Foundations
Lutz Johnen, Chairman of the UK Rainwater Management Association, discusses
why water supply solutions should be a consideration when designing a new homeRAINWATER
HARVESTING
W
ater supplies
under stress
DEFR A’s recently
published progress
report on the
Government’s
25-Year Plan for the Environment makes
interesting reading for any environmentally
conscious self-builder, not least where it relates
to water. Acknowledging existing stresses on
water supplies, and the additional increased
pressures likely to arise in the coming years from
population growth and climate-change, one
of the key aims of the Government’s Plan is to
ensure adequate future supplies of good quality
water for both people and the environment.
The growing challenge in this respect is
illustrated by the graphic (right), which shows
the water-related difficulties already being
faced by agriculture and, by implication, the
natural environment.
It is therefore hardly surprising that theplan aims to tackle the challenge in part, by
aiming further to reduce domestic mains-
water consumption below current Building
Regulations requirements.Making better use of available water
By far the most straightforward way of doing
that would be to make rainwater harvesting
systems as normal a feature of a new UK
house, as is already the case on mainland
Europe in countries experiencing similar
water-supply stresses.
Rainwater harvesting systems are very
straightforward to install in new-build homes;
they operate simply by gathering roof water
via standard guttering and downpipes, then
filtering-out solid matter before storing it
underground for later re-use. The storage
tanks are sized according to the roof area and
occupancy of the property concerned, to provide
around 20-days consumption in dry weather
from full. The stored water is then deliveredthrough dedicated pipework to services that do
not require potable water, typically the toilets,
clothes-washing machine and garden tap.Saving precious mains-water
Current Building Regulations require new
homes to be designed and built so that they
use no more mains-water than 125-litres
per person per day, on average; generally,
this can be achieved by a combination of water-
efficient appliances, smaller baths and wash-
hand basins and sinks, and water-efficient
taps and shower-heads.
To reduce average daily consumption
significantly below the current requirements
will mean either having new homes without
baths, or the substitution of harvested
rainwater for some of the mains water that
would otherwise be used. Typically, this
latter approach would reduce the mains-
water consumption down to around 80-litres
per person per day. And, better still for keen
gardeners, if designed-in from the outset, the
system can also be a source of garden irrigation
water – even when hosepipe bans are enforced.http://www.ukrma.org