Looking after the grey matter

Sustainability is on the government’s agenda, but its strategy is focussed

heavily on reducing fossil fuel consumption and global warming, with water taking

something of a back seat. Yet water is arguably more important than energy,

especially for biodiversity, food production and public health. And, like energy,

water supplies are finite.

As a nation we have become water guzzlers and the problem is likely to grow.

Between 1989 and 1991, which were not particularly dry years, 178 drought orders

were issued. But even without drought, there would be cause for worry. In the

UK, household water consumption has risen by 70% over the last thirty years,

yet we still regard water as a cheap, abundant commodity.

In January 1992, the United Nations held a world water conference in Dublin

which tried to promote water conservation, prompting various governments, including

ours, to act.

The Water Supply Regulations in England and Wales and equivalent byelaws have

put in place some simple and practical water conservation measures. All newly-

installed WCs must use a 6-litre maximum flush compared with the 7.5 litres

and above allowed previously. The 20% water savings will benefit the metered

customer and the environment. Dual-flush WCs are permitted with a smaller flush

of no more than two-thirds of the maximum.

It is a start. However, if the government and water industry is serious about

their stated objective of sustainable development then there is still much work

to be done. It is the government’s responsibility to educate society about water

conservation. For instance, in addition to the conservation techniques already

mentioned, there are two other easy ways which house builders and designers

can use to conserve and manage water: harvesting, filtering and storing rainwater

and grey-water recycling. Unfortunately the government has left it to vendors

of such technologies to preach the gospel. And, rightly or wrongly, UK businesses

are sceptical of the salesman who comes knocking on the door with a piece of

equipment guaranteed to save money.

Water Dynamics, one of the leaders in grey-water recycling, is the only United

Kingdom Accreditation Service-accredited manufacturer of water recovery systems.

“Unfortunately we struggle with public perception of grey-water recycling

from communal sources,” said Water Dynamics’ marketing manager Lora Lee

Brown. The argument for using grey water for flushing toilets is strong when

you consider mains water used for flushing toilets is of drinking quality. It

clearly does not have to be of such a high standard, although it should not

pose a health hazard.

LA Story

The Office of Water Reclamation of the City of Los Angeles completed a project

on grey-water re-use, which involved looking at eight test systems. Health worries

centred on the use of water for garden watering rather than flushing the toilet,

but the project found that grey water did not present health risks as long as

reasonable sanitary practices are followed.

Water Dynamics’ units designed to be ‘fit and forget’. Regardless of the size

of building, if it uses water – particularly in large quantities – the company

believes it can design a bespoke, accredited system which will achieve a 40%

saving in water consumption. Maintenance requirements are minimal and the units

are claimed to have reasonable pay-back periods.

Water Dynamics’ system does not synchronise grey-water supply and demand, instead

it ensures either grey water or mains water will always be available. Continuity

of supply to the toilet is maintained independently of grey-water production

by the system automatically switching to mains water if there is not enough

grey water. Excess grey water is automatically discharged to the drain.

The recycling system’s storage capacity is based on normal toilet operation,

calculated at 180 litres for a typical day. By storing only a limited amount

of water, and by storing that water for only a short period of time, it has

been possible to eliminate traditional engineering, hygiene and economic problems.

Grey water is pumped from the storage reservoir to a break tank, which incorporates

the mains water supply mechanism and provides a gravity feed to toilets. The break tank has been designed

so that the grey water cannot contaminate mains supply. Water supplies from

the storage reservoir are chemically treated as they enter the break tank by

passing through a dispenser of slow-dissolving bromine tablets. This provides controlled dosage

for one year, without releasing any more chemicals to the environment than are

used for lavatory bowl cleaning. Under normal conditions, Water Dynamics’ recycling

system is self-cleaning.

A filter is used to purify the water to between 60 to 80µm. After filtration,

a brominator provides residual disinfectant to ensure Legionella, E. coli, organic

growth and other bacteria are prevented. The filter elements receive a spray

of disinfected water from the break tank after every pumping cycle. This keeps

the filter chamber clean, prevents saponification and assists disinfection of

the water in the storage reservoir.

Water Dynamics has been involved in extensive water recycling trials and pilot

schemes with water companies and developers resulting in WIMLAS Technical Approvals/Building

Research Establishment (BRE) accreditation. The company sees this as a milestone

because the National House Building Council (NHBC) has stipulated it will not

cover any non-accredited water recycling systems. The field of grey-water recycling

is growing in sophistication believes Brown: “In all honesty, with something

as new as water recycling there are no text books with all the answers, but

through extensive trials with the Building Services Research and Information

Association (BSRIA), the Construction Industry Research and Information Association

(CIRIA), BRE, Cranfield University, Wessex Water, Gleeson Homes, Crest Homes

and Three Valleys Water to name but a few, we have learned and adapted our systems

to overcome teething problems.”

It also appears that public awareness and demand for water-efficient devices

is growing. According to Peter Casey of Gleeson Homes: “Water efficiency

was rated as a very important factor among potential home-buyers. In our latest

survey 62% of potential house-buyers said they would pay more for a home with

water-saving features which offered long-term cost savings.”

With so many water saving techniques available, one has to wonder why the government

and water companies are not promoting them as part of the drive for sustainability.

By offering significant incentives to companies willing to invest in the recycling

technology, it is within the government’s power to ensure grey-water recycling

becomes an integral part of our society.