The future’s grey

Innovative thinking can offer new solutions to managing water consumption. Hamilton Scanlon explains the technology behind greywater reuse systems.
Newly-launched technology is now enabling users to make more use of their water supply without any form of rationing or disruption to their existing lifestyle. Designed for use in residential, commercial and municipal properties, this water-saving solution enables the collection of waste-water (greywater) from baths and showers, and in some cases sinks, and recycles it for use in flushing toilets.
Suitable for retrofit as well as new-build, greywater reuse systems reduce the mains water needs of a house or building by up to 30% and are designed to be easy to install and use. A revised plumbing set up takes all waste-water from baths and showers, redirecting it through a filtration unit where it is treated with a disinfectant. This treated water is collected in a tank and piped on, as required, to supply all the flushing water needs for multiple toilets in the building.
Once fitted, the water saving opportunities are compelling and have the potential to make a big contribution to reducing water demand across the UK. Based on daily usage figures of 150 litres of water per person (figures from the UK organisation, Waterwise), a family of five will typically save around 80,000 litres of water each year – the equivalent of over 1,000 baths, more than 1,600 loads of washing or about 328,000 cups of tea.
As most buildings in the UK have only one water supply, until now there has been little option but to put up with the confused logic of using drinking quality water to flush our toilets. But with increasing pressure on our water supply from droughts, increased population etc, greywater reuse technology has the potential to make a big contribution to reducing water demand across the UK.
Enhancement option
An optional feature on certain greywater systems can also reduce energy consumption by fitting a heat exchanger to the grey water reuse link between the bath, shower and toilet flush. This allows heat to be extracted from the building’s greywater – before it’s recycled – so it can be fed back into the central heating system. As well as reducing fuel bills, this addition results in a two-fold reduction in CO2 emissions.
The technology’s relevance and appeal stretches beyond those with an environmental conscience and specifiers and developers to any householders or business owners whose properties are in metered areas. End users will benefit from significant annual savings on their water bills.
Using recycled grey water – as opposed to high-quality drinking water – leads to a reduction in the carbon footprint of a home or project. It contributes to the project’s environmental sustainability and complies with specific planning conditions as well as key standards – in particular, the Code for Sustainable Homes (CSH.
The link between greywater technology and achieving a higher rating under the CSH has already been made by Ideal Standard. It has teamed up with greywater specialists (Reaqua Systems) and code assessors (Stroma) to offer a specific package of greywater and sanitaryware options for the specifier or end user which, if fitted in combination, are guaranteed to elevate any build project to a Code 5/6 for water efficiency.
Stroma Certification’s Stuart Oakes also believes that this new arrangement will make it a lot simpler for anyone – whether a specifier, installer, developer or self-builder – to fit this greywater system with approved sanitaryware and meet the requirements for water efficiency under a Code 5/6 rating.
Comparisons with other water saving measures
Greywater reuse overcomes the problems associated with other demand management solutions such as rainwater harvesting. In the case of greywater, supply is predictable and constant as it is not dependent upon the weather, unlike harvesting where available rainwater is used to augment the water supply to a building.
Rainwater harvesting also requires large scale tanks and long storage times to cope with seasonal variations – both of which create further problems of cost and water quality. If demand suddenly increases, the greywater solution scales accordingly – more baths and showers means more water for toilet flushing.
There are other benefits too. Greywater has a consistent level of acidity, and, unlike rainwater, it is always just above room temperature – avoiding the formation of condensation on toilet cisterns and the cooling of the bathroom.
Companies operating in this sector are seeing an increasing number of projects – even at the point of breaking ground – switching from rainwater harvesting to greywater reuse technology to deliver a more appropriate and cost-effective solution that still meets the flushing needs of a building or new housing development.
As well as offering more consistent water quality, the significantly lower capital cost associated with specifying and installing greywater reuse technology seems to be really driving its popularity.
Greywater reuse systems can obviate the need for fitting water rationing and flow restricting technology such as low-flush toilets or low-flow showers.  Where the latter are fitted, it can often lead to disappointingly low flow rates from showers or, worse, blocked waste pipes.
Research has shown that using low-flush toilets may not provide sufficient movement in small pipes to carry away solids, leading to blockages and flooding.
From a householder’s point of view, the greywater reuse solution means they do not need to make any lifestyle or behavioural changes. Even though water consumption is reduced, bathing comfort is always maintained and adequate water is available to clear drains through flushing.