London law school set to reap rewards from rainwater harvesting

City, University of London is set to install a rainwater harvesting system at its new £42m law school, in a move which could reduce its water costs by more than £4,500 each year.

The standalone rainwater harvesting system, provided by water management firm Waterscan, will operate in conjunction with attenuation water storage, collecting and storing rainwater before filtering it through a treatment system. The University will then be able to reuse it for non-potable applications including toilet flushing.

The rainwater harvesting system will help the University contribute to London’s long-term urban infrastructure planning and sustainable development goals, as outlined in the London Plan and newly-finalised London Environment Strategy (LES). 

“The London Plan encourages the reuse of water and we worked through various options for this project including greywater recycling to intelligent attenuation,” Waterscan’s director of operations Barry Millar said. 

“Tight space onsite led to us recommending and creating a bespoke combined rainwater harvesting system complete with attenuation – an exceptionally cost-effective solution when balancing spatial and environmental considerations.”

Water savings 

The City Law School, which is set to open in early 2019, has several built-in sustainability features including a car-free zone, secure cycle parking and tree planting.

Waterscan anticipates that choosing the rainwater harvesting system will save the University £4,500 per year compared to using entirely mains water, as the water reuse system can produce one cubic metre of water, using just 1.5kW/h energy. For buildings which have adequate roof space to collect and store water to achieve a good return on investment, it is estimated that a rainwater harvesting system can reduce mains water consumption by up to 30%.

The London Plan requires all new residential buildings to incorporate water-saving measures and equipment in their designs so that mains water consumption can meet a target of 105 litres or less per head per day.

Sarah George 

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