Sustainability for the future 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.
A nation of guzzlers
As a nation we have become great water guzzlers, and the demands that modern
society makes upon the water supply mean the water issue will not go away. Between
1989 and 1991, no fewer than 178 drought orders were issued. Even without drought,
there would be cause for worry. In the UK, water consumption in households has
risen by 70 per cent since 1970. Yet we still regard water as a cheap and 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 bylaws have
put in place some very simple and practical water supply solutions. All newly
installed WC’s must use a six litre maximum flush compared with 7.5 litres and
above previously. Sensible when you think that the 20 per cent water savings
will benefit both the metered customer and the environment. Also, dual flush
toilets are permitted with a smaller flush no more than two-thirds of the maximum.
It is certainly a start. However, if the government and water industries are
serious about their stated objective of ‘sustainable development’ then there
is still much work to be done in the water conservation department. It is the
government’s responsibility to educate society about water conservation.
For instance, in addition to the simple water conservation techniques already
mentioned, there are two other sensible and easy ways in which those responsible
for designing and building might consider conserving and managing water: harvesting
rainwater from the roof, filtering and storing it for later use and recycling
water that has already been used (commonly referred to as ‘grey water recycling’).
Unfortunately the government has left it to the vendors of such technologies
to blow their own horns. And, unfortunately, UK businesses are traditionally
sceptical of the salesman who comes knocking on the door with a piece of equipment
guaranteed to save money.
Grey water recycling
Water Dynamics Ltd, one of the leaders in grey water recycling, is the only
United Kingdom Accreditation Service-accredited manufacturer of water recovery
systems.
Water Dynamics’ marketing manager Lora Lee Brown, acknowledges the current
situation, “Unfortunately we struggle with public perception of grey water
recycling from communal sources,” she says. The argument for using grey
water for flushing toilets is strong when you consider that water from the mains
used for flushing toilets is of drinking quality. It clearly does not have to
be of such a high standard, although equally, it should not pose a health hazard.
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 findings were that grey water does not raise the health risks so long
as reasonable sanitary practices are followed.
Water Dynamics units are as simple as ‘fit and forget’. Regardless of the size
of your building, if it uses water – particularly in large quantities – Water
Dynamics claims it can design a bespoke accredited system that will achieve
a 40 per cent saving in water consumption: the greater the use, the greater
the saving! Maintenance requirements are minimal and the units are claimed to
have reasonable pay back periods.
The system makes no attempt to balance or synchronise grey water supply and
demand; instead, it ensures that 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. If there is excess grey water it is automatically
discharged to the drain.
Water storage capacity in the recycling system is only what is needed for normal
toilet operation, calculated at 180 litres (40 gallons) 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.
How does it work in practice? Grey water is pumped from a storage reservoir
to a header tank, known as the ‘Break Tank’, which incorporates the mains water
supply mechanism and also 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 before they
enter the Break Tank by passing through a dispenser of slow dissolving bromine
tablets. This process provides yearlong controlled dosage without adding more
chemicals to the environment than is used for lavatory bowl cleaning. Under
normal conditions, Water Dynamic’s grey water recycling system is self-cleaning.
A high quality filter is used to purify the water to between 60 to 80 microns.
After filtration, a brominator or disinfectant chamber will provide residual
disinfectant to the system ensuring that Legionella, E. coli, organic
growth and other bacterial attack are all catered for.
The filter elements receive a spray of disinfected water from the break tank
after every pumping cycle. This keeps the filter chamber fresh and hygienic,
prevents saponification in the filter pores and goes on to produce on-going
disinfection of the water in the storage reservoir. These processes keep the
filter elements effective for month after month of continuous, maintenance free
use.
Water Dynamics have been fortunate enough to be involved in extensive water
recycling trials and pilot schemes with water companies and developers resulting
in WIMLAS/BRE accreditation. It is great mile stone because NHBC have now stipulated
that they will not cover any non-accredited water recycling systems.
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 BSRIA,
CIRIA, BRE, Cranfield University, Wessex Water, Gleeson Homes, Crest Homes,
Three Valleys Water to name but a few, we have inevitably learned and adapted
our systems to overcome teething problems.”
Public perception
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 a very important factor among potential home-buyers in our latest
survey – 62 per cent of potential house-buyers said they would pay more for
a home with water saving features that offered long term cost savings.”
With so many water saving devises and methods available to us, one has to wonder
why the government and water companies aren’t making it a necessary part of
sustainability for our future. By offering significant incentives/grants to
those companies willing to invest in the recycling technology, the government
has it within their power to ensure that grey water recycling becomes an integral
part of our society.
Grey and rain water systems are probably the easiest and most environmentally
friendly systems; however, other choices are available:
- Composting, waterless WC’s. There is a wide range available for a number
of different applications. These are literally waterless, using no water at
all. However problems include the high cost of installation, user acceptability
and the perception of maintenance and cleaning as a ‘dirty job’.
- A one-litre flush composting WC. The flush gives the user the impression
that they are using a conventional lavatory.
- Urine-separating-style lavatories where the sterile and nutrient rich urine
is never mixed with the potentially diseased and nutrient poor faecal material.
The separated urine can be diluted and used directly as a fertiliser or passed
through a carbon rich compost bed over the winter months.
- Waterless male urinal systems, using a urinal coating and a perfumed oil-filled
trap with quarterly maintenance. Again, the urine can be taken for direct
land use. There is also a range of systems that require a water flush as a
transport mechanism but are more environmentally desirable than a conventional
system.
- Reed beds which can treat sewage and grey wastewater. These require a large
area of land and specialist maintenance and cropping for nutrient recycling.
- An aqua solar system that can treat sewage and grey water in a complete
ecological system within a greenhouse. This system also requires specialist
maintenance and cropping for nutrient recycling.
- Septic tank or small-scale package treatment plants can give nutrient recovery
back to the land via leach fields, but may need tanker emptying.
- Anaerobic digesters treat sludge, recycle nutrients and produce methane,
which can be used as a power source but are expensive for small systems.
© Faversham House Ltd 2023 edie news articles may be copied or forwarded for individual use only. No other reproduction or distribution is permitted without prior written consent.
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