… looking forward to April showers …

About the author

Lutz Johnen is Chairman of the UK Rainwater Management Association, an organisation dedicated to helping address the UK’s developing crisis in mains water supplies.

Recognising the problem

The Government has for many years publicised the need to economise on water consumption as the dual effects of a growing population and changing rainfall patterns caused by climate change have increasingly placed strains on mains water-supplies in the drier and most highly populated parts of the country.

For the most part, the general population has remained indifferent to this problem which is judged in part not to exist (it’s always raining isn’t it?), and in part to leaking infrastructure that simply needs to be repaired (ie someone else’s fault); real-politik, however, is somewhat different.

It may be true that we are losing more water than we should due to leaking infrastructure, but it would be wise to acknowledge that this is unlikely to be a problem that can be easily or speedily rectified.  Meanwhile, and inexorably, the population continues growing, and patterns of rainfall continue to change.

and its causes

The Environment Agency is predicting (“Water for People and the Environment”) that within the lifetime of everyone aged under-40 today, the population of the UK will have increased by around 20-million.

At the same time, and already, the pattern of rainfall is altering due to climate change so that the UK’s traditional combination of frequent spells of steady moderate rain is giving way to combinations of longer drier spells coupled to shorter periods of more intense downpours.

The overall anticipated impact of these factors is reflected on the Environment Agency map shown, which predicts that rain available for collection will be reduced by between 10% and 15% causing, in turn, summer river levels to be down by between 50% and 80%.  Against this background, rainwater harvesting and greywater recycling will become important sources of the water needed to meet population growth over coming years.

and its causes

The Environment Agency is predicting (“Water for People and the Environment”) that within the lifetime of everyone aged under-40 today, the population of the UK will have increased by around 20-million.

At the same time, and already, the pattern of rainfall is altering due to climate change so that the UK’s traditional combination of frequent spells of steady moderate rain is giving way to combinations of longer drier spells coupled to shorter periods of more intense downpours.

The overall anticipated impact of these factors is reflected on the Environment Agency map shown, which predicts that rain available for collection will be reduced by between 10% and 15% causing, in turn, summer river levels to be down by between 50% and 80%.  Against this background, rainwater harvesting and greywater recycling will become important sources of the water needed to meet population growth over coming years.

and solutions

Uniquely, rainwater harvesting (RWH) systems have a role to play both in response to water shortages, and in helping to ameliorate flood risks.  These systems are very straightforward to install in new-build homes and commercial developments, and operate on the two basic principles illustrated (ie “direct-pressure” and “via a header-tank”.

The principle used does not affect the amount of mains-water that can be saved by substituting harvested rainwater for non-potable applications such as toilet-flushing, clothes-washing, and the outside tap.  Each type of system has its own respective features and benefits, with the direct pressure version pumping the stored rainwater direct to the services on-demand.  The header-tank version stores the rainwater in a similar way, but provides the water to services via a header-tank.