Regulated Water Management

This may sound a surprising assertion on the face of it, but we expect that within a few years every UK new build domestic house will have rainwater harvesting equipment installed as standard. Without it, developers and builders will not be able to meet the requirement for water usage laid down in the Code for Sustainable Homes.

By Mike Norton, Technical Director, Kingspan Water and Chair UK Rainwater Harvesting Association.

It underlines just how far up the public agenda the need for sustainable water usage has come.

Global warming has meant that government and industry has had to engage in a candid review of our water resources; one which is likely to lead to significant changes in how we all use treated water. And one in which means many people are going to have to put greater value on the water they use. The consequences of climate change will almost certainly result in a limit being imposed on individual water usage, with future generations having to mange in a world where consumption rates are less than half those currently.

As better management of water resources has become a priority, so we have seen the introduction of building assessments and regulations to improve water usage in new developments.

Two building assessments in particular, the Code for Sustainable Homes and BREEAM rating, have had a major influence in supporting a sustainable water programme in this sector. Both schemes require that limits are imposed on mains water consumption in order for a development to achieve an excellence rating.


In the public sector, Level 3 of the Code became mandatory in 2007. It will become mandatory for the private sector this year.

The higher Levels are being more gradually phased in over the next few years: all new homes, of course, must be Level 6 by 2016.

The significance for rainwater harvesting is that achieving a Level 5 or 6 rating requires a reduction in mains water consumption in a property from an average of 160 litres per person per day, to as little as 80 litres (WAT1 and WAT2 of the Code). Quite a difference!

That said, modern, high-density housing can limit the average roof area of a house to around 40m2 which may represent a restraining factor on the capacity of any rainwater harvesting system and its ability to deliver the savings required by the Code. For this reason, installing water reuse or “greywater recycling systems” as well as rainwater harvesting may become more common in the future.

Aside from sustainable water use, there are other mandatory parts of the Code relating to water management that are perhaps not so widely appreciated, in particular SUR1.

Under SURI, developers are obliged, ‘To design housing developments which avoid, reduce and delay the discharge of rainfall to public sewers and watercourses. This will protect watercourses and reduce the risk of localised flooding, pollution and other environmental damage’.

This aspect of the Code has been designed to align with planning policy statement PPS25: ‘Development and Flood Risk’ and with the CIRIA ‘Interim Code of Practice for Sustainable Drainage Systems (SUDS)’.

SUR1 requires the installation of rainwater harvesting as a first option if the ground conditions require it in order to reduce surface water run-off.

By capturing rainwater from the roof via the guttering, and storing it on site, a rainwater harvesting system can reduce surface run-off during heavy rainfall. The recycled water is then passed (via the washing machine or toilet) into the foul system rather than directly into storm drains, reducing the flood risk associated with overflowing drains.

If issues around surface water run-off are not addressed, a development will only qualify for a Level Zero rating so the consequences of ignoring SUR1 are far-reaching.


Alongside the Code, we have the Building Research Establishment Environmental Assessment Method (BREEAM) – one of the most widespread and comprehensive assessments designed to recognise the environmental performance of a building through a scale rating.

Most new-build schools, colleges, offices, government buildings, multi-residential and retail buildings should now be designed to meet a high BREEAM rating. Every available point needs to be secured to reach an excellent standard, therefore rainwater harvesting, which gives points in a couple of categories, will often be installed.


Finally, we understand that water management will be a focus for the incoming Building Regulations G due to be published in April 2010. For the first time, they are expected to set out limits for water consumption – possibly around 125 litres per person, per day.

How and where greywater recycling and rainwater harvesting may be used in new build projects is also expected to be set out in these regulations.


There has been much debate as to whether water metering should be a requirement alongside all the regulations. The issue underpinning both regulation and metering is the need to encourage people to place greater value on water, and therefore use it more judiciously.

But how is any level of restraint going to be received by consumers, who may feel metering is yet another infringement on their liberty, and simply a way of passing on rising costs to the beleaguered tax-payer?

As with all attempts to persuade people to change their habits, it’s useful to employ the carrot as much as the stick. It’s therefore encouraging to note that rainwater harvesting can play a further part in advancing this discussion.

Rainwater harvesting not only reduces dependency on mains water, it also delivers significant financial savings for consumers. When rainwater and greywater systems are used together, savings of up to 50% on a domestic property’s annual water bill can be realised (although this is impacted by factors such as the size of the roof and the annual rainfall in the region).

Whichever way you look at it, rainwater harvesting has to be seen as an important part of our future – a truly joined-up approach to sustainable water management.

For more information, visit, download our guide at

Action inspires action. Stay ahead of the curve with sustainability and energy newsletters from edie