Project no. 130
RainFlush, Water Preservation and Security
I. L. Nikolajsen, L. Hamre, C. Askgaard, C. Frøsig, L. F. Skovgaard,
C. Holm og O. T. Scheel
DTU Process and Innovation, Technical University of Denmark
THE ISSUE AT HAND
In Denmark we’re fortuned to have a vast amount of drinkable water in our sub terrain. Due
to this, the lack of access to clean water, has never been a proper concern of the Danish
Our vast deposit of clean water is, however, shrinking at a rapid pace. The reduction in the
amount of clean water in the Danish sub terrain, is partly due to contamination by pesticides,
originating from the agriculture utilizing the land, and general pollution, but the main issue is
that our consumption of water is higher, than the rate of replenishment. This consumption
includes, about a third of the total consumption per person, literally being flushed down the
At the same time, Denmark is a country, with a massive amount of downpour every year, a
resource we’re not yet using in any mentionable scale. According to DMI, Danish
Meteorological Institute, there have been an increase in downpour of 100 mm, over the last
150 years. Further research indicates, that the amount of downpour will increase with
between 1,6 and 6,9 percent.
The increase of downpour is already visible, in the number of cloudburst per year, leading to
an increased number of floods in the urban areas.
Our solution, RainFlush, consist of a water gathering system, that will collect rainwater,
through the buildings own drainage system and store it in an underground storage tank. This
water will be utilized as a replacement, for drinking water in our toilets. This way, we will
potentially reduce the consumption per person, by almost a third. Hereby the rate, at which
we spend our water reserve below the surface. Furthermore, the user will experience an
economic advantage, as the total amount of money, paid for water, will decrease.
Where our system really differentiate from existing solutions, is the ability to deplete the
storage tanks, ahead of a cloudburst.
The storage tank will after this serve as a storage for heavy downpour. During a cloudburst,
the downpour will supply more water, than the sewer system can manage leading to
overflowing and floods. Using RainFlush will extend the waterflow to the sewers and hereby
prevent the flood.
WHAT THE FUTURE HOLDS
As technology improves, we will gain the opportunity to increase the volume of rain water
being used in the household. As of now, purifying rain water for cooking and drinking is
possible, but not feasible at a household level. We hope to extend our system, when the
technology becomes available and hereby reduce the consumption of our water reserves
In this way, we hope to secure a clean and consistent supply of drinking water for all future