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LANDSCAPING & EXTERNAL WORKS
businesses in Sussex are already having to live with. How long will it be before other places follow suit?
When you know that water will run out if you use too much of it, you have a different mentality. My career in the water industry has partly been forged in this contrast: when I came to live in Britain from Australia an adult, it seemed to me to be raining all the time! Yet, now 80% of the UK is classed as water-stressed. That would baffle most Australians.
Rainwater recycling is one of the oldest, and simplest, water technologies; systems do not need to be complicated or expensive
How do we even begin to calculate our water footprint and aim to become water neutral? Most of us would find it difficult to know where to start. Before we even begin, we must assign water its true value. The Hollywood actor Matt Damon famously made people stop and think about the value of water in a stunt at one American hotel. Guests were denied water for six hours. It made them angry. Then they were shown a film showing them what it is like for millions of people in the developing world who have to walk six hours a day just to get water to survive. It made them cry. The video “The Wait for Water” is on YouTube.
Some parts of the UK are at serious risk of not having enough water in less than 20 years. The dual forces of population growth and a straining water infrastructure have led to massive pressure on our water supply. Yet, compared to other European countries, water here is cheap; most people expect water to be almost infinitely and freely available.
Our demand for water will continue to exceed supply until we attach greater value to it and manage it properly. In other countries, people are used to restrictions with their mains water usage. Yet, many people in the UK feel affronted if they are even prevented from watering their lawns for just a few days. In Australia, basic rainwater harvesting systems are commonplace. Rainwater recycling is one of the oldest, and simplest, water technologies; systems do not need to be complicated or expensive. If water reuse were widely introduced in homes across the UK, it would go a long way to closing the gap between predicted demand and supply.
Collect rainwater at source Just as we are waking up to the concept of managing rainwater at source to prevent flooding, we need to consider water consumption in the same way. We waste heavily treated mains drinking water,
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flushing 30% of it straight down the toilet. Instead of reusing it, we send excess water into our sewers; instead of capturing it where it falls, we allow rainwater to flow off our roofs and drive into an overloaded drainage infrastructure.
Despite their position in CIRIA’s SuDS Manual – widely acknowledged as the bible for designers and consulting engineers – at the top of the design hierarchy, rainwater harvesting and reuse systems, while a relatively simple technology and established for many years, have failed to become mainstream.
One barrier to progress has been the need for most rainwater harvesting systems to be designed with a second attenuation or storage tank to manage flood risk. Now, advances in smart instrumentation and telemetry are being harnessed, so that the storage space needed for flood control and water-saving can be combined in just one tank. Leading technologies, beginning to be deployed in the UK, use weather prediction data to control the levels of rainwater in this single tank for both attenuation and reuse. When a storm is predicted, the water level in the tank is lowered in plenty of time to allow the spare capacity to be used as a defence against surface water flooding. Such technologies can be deployed for commercial or public buildings and also at a single domestic property, street, or community level in housing developments. They have already helped numerous developments to secure top BREEAM sustainability ratings, particularly in London where they benefit from support in the London Plan and GLA SuDS guidance. Advances in ‘smart’ instrumentation, telemetry and cloud-based management and monitoring systems extend the capabilities of intelligent rainwater reuse systems still further. A digital cloud-based system can provide a wealth of data on system performance in order to better plan maintenance and demonstrate water savings in real-time. Every business case for rainwater harvesting is different, and expert organisations can advise on feasibility, correct sizing and calculate the financial justifications. These dual-purpose systems, that mitigate flooding and provide water for reuse at the same time, can make a real difference to future demand management in the UK. It’s time to think water neutral.
Adam Dean is business development manager water reuse at SDS
ADF JUNE 2022
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