Enabling Water Smart Communities. A vote of confidence in communal rainwater harvesting

The Enabling Water Smart Communities project brings together water industry professionals to improve water efficiency in the built environment. The project, funded by the OFWAT Innovation Fund, recently published a new report detailing an assessment of options and a full business case for rainwater harvesting and greywater recycling in the UK.

In this week’s blog, we take a look at what this vote of support means for the implementation of dual pipework water reuse systems in the UK. The importance of this report should not be underestimated, and it sends a clear message to policymakers that water reuse technologies must become standard in the country if our future housing infrastructure is to cope with increasing population density and increased climate change.

Setting the scene

Why is this report so important? There are two reasons…

Water efficiency

The national water deficit predicted in the UK by 2050 stands at 5 billion litres, despite the public perception that England is a water-rich nation.

You may not know that our building standards specify homes are built to a standard rate of 125 litres per person per day (lpppd). Water companies also have powers in regions where serious water stress is an issue to specify that homes are built to a reduced rate of 110 lpppd.

Now, there are growing calls to reduce this rate even further to ensure future water security. The size of reductions being called for by the industry means that water reuse will play a fundamental role.

Legislation

This report is crucial as it addresses some of the key regulatory barriers to the widespread implementation of rainwater harvesting in homes. Whilst implementation of water reuse is easily achieved in non-domestic properties, a number of regulatory hurdles exist in relation to communal-based reuse systems.

About water reuse

Water Reuse is a relatively new term for the industry – but what is it?

Water reuse can be thought of in two ways; on a large scale, with indirect potable reuse (this is how our drinking water is cleaned), or on a smaller scale. Smaller scale examples include capturing and recycling rainwater or greywater on an individual home or communal development scale.

Interestingly, the report also covers the capturing and recycling of stormwater. Unlike rainwater harvesting, stormwater harvesting collects from roof areas and hard-standing areas.

Water reuse requires a separate network of pipework to the mains potable supply, often referred to as the “dual pipework” approach.

Key findings in relation to water reuse

So, what did the project’s research team find out?

Rainwater Harvesting

Overall, communal-based rainwater harvesting systems were the most cost-effective solution. Communal-based systems collect water from multiple properties in a central system for recycling across the development.

The cost analysis did not just consider the capital cost of the rainwater harvesting system, but also the additional pipework requirements.

In contrast, individual-plot rainwater harvesting systems (a system per home) become increasingly less cost-effective as the number of properties in the development increases.

Average cost findings for rainwater harvesting

Communal rainwater harvesting = £2,000 per home.

Individual plot rainwater harvesting = £4,000 per home.

Greywater recycling

For greywater recycling, the picture is slightly different depending on the type of residential development. It is worth noting here that the project team identified that there is a need to get more information on the external pipework requirements to ensure a more accurate figure.

For standard homes, individual-plot greywater recycling systems were more cost-effective than communal-based greywater recycling systems due to the additional pipework requirements.

However, this story changes again when we look at high-density residential developments such as apartments where a communal-based system would be the more cost-effective approach.

Summary

Concluding the report, the project team identified that communal rainwater harvesting “indeed appears to be most cost-effective than individual-plot rainwater harvesting at all development scales”.

Stormsaver is wholly supportive of this report and was delighted to work with Enabling Water Smart Communities, along with others, to provide more information on the capital costs of our systems.

We would encourage you to find out more about the project here and read the full report here.

If you would like to learn more about how communal rainwater harvesting works, find more information here.

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