Arup is working with a toilet inventor on a novel system that uses air assistance to generate a maximum of 1.5 litres of water per flush, compared with typical dual flush toilets which use between four and six litres.

The engineering firm has developed a universal connector so that it can be fitted to existing drainage systems and is currently testing it within two of its London offices.

According to Arup’s global skills leader for environmental services engineering, Martin Shouler, toilet design hasn’t fundamentally changed much since the Victorian era. Blogging on the company’s website, he wrote: “In the UK, toilet flushing accounts for around 30% of household water use. That’s a lot of drinking quality water going down the pan.”

The company is also looking at ways businesses can combine efficient toilet designs with harvested rainwater and recycled water, through the sourcing of non-potable water from community-scale networks.

“Just as distributed energy taps into local sources of heat or electricity, water reuse networks would tap into suitable sources of rainwater and treated wastewater and match them to demand for flushing and other purposes such as irrigation,” Shouler noted.

“You could flush your toilet with water piped from the local leisure centre, for example, saving both potable water and the energy used to treat it.” 

New opportunities

Such systems would complement rather than replace existing water supply and wastewater infrastructure, he added, but pointed out that it would provide opportunities for both businesses and householders to save water, energy and money.

“It could even give traditional water utility companies the opportunity to develop networks outside their geographic areas and provide opportunities for new entrants in the water supply market.”

The social feasibility of urban water reuse networks is being explored by a number of firms and institutions, Arup included. Traditionally the UK hasn’t relied on such networks due to sufficient supplies of water, but increasing demand for water – particularly in the South East – has seen recent moves to establish these networks as part of a sustainable cities agenda.

Maxine Perella

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