ECOCLUB, Issue 90
15
filter that makes the water suitable to be used in their garden. At Lost Valley International Community and Educational Centre,
there is a simple version of the rooftop flowerbed system in place where water from the sink drains into two bathtubs filled with
plants that filter the water, which is subsequently transported to other plants in need of water. In the Jemby Rinjah lodge in
Australia, grey water is dealt with by a series of five sequential grey water tanks constructed of recycled plastic, which ensure
that no waste material leaves the site. After treatment, water is disposed of by transpiration through a switchable dual trench
system.
As described in the above examples, the main use of grey water in ecolodges is for irrigation of flower gardens and trees,
however it is not recommended for use on vegetables that are eaten raw. Grey water can also be simply collected in ponds and
used to produce algae to feed fish in a separate pond, or provide food for ducks and other waterfowl. Yet another use for grey
water is for flushing toilets, however it is still not economically or environmentally friendly enough to treat grey water for this
use, mainly because storage of grey water results in high levels of bacterial contamination. A recent innovation in grey water
recycling (that does however require the utilisation of chemicals), the AQUS system, has focused on this particular weakness of
most grey water systems. It utilises grey water from the bathroom sink to flush the toilet via a compact purification and pump
system that renders the water safe for pets and humans (although not potable).
DIY Grey Water Recycling
Considering the average household creates 83,000 litres of grey water annually, you might think of recycling your grey water -
you could save up to 50% off your water bill! Depending on the country you are in, various legislative measures apply regarding
grey water recycling, which you should check before installing your DIY grey water recycling system. As a general rule it is
best to avoid irrigating gardens when your grey water has high concentrations of detergents that have a high phosphorus and salt
content.
The first step to DIY grey water recycling is to pass it through a coarse filter to remove large particles. Then, this water needs to
be channelled through a sand filter. Basically, this is made up of a thin layer of gravel topped off with a much thicker layer of
sand within a waterproof container (old plastic dustbin, water butt, or barrel/drum). Coarsely filtered water passes through the
sand, being finely filtered as it goes, before emerging at the bottom. The deeper the layer of sand, the better the filtration. For
further filtration, this water can then be passed through a box containing water-loving plants or reeds, that will remove any
traces of phosphorus (that is harmful to certain plant varieties), salt (present in most detergents) and other nutrients.
You should be especially careful with distributing your filtered grey water. This should be done by subsurface irrigation (e.g.
porous hoses) avoiding sprinklers and any possible human contact. Over watering plants over periods of increased occupancy
has been observed as a potential problem with grey water recycling, so grey water distribution must be closely monitored.
Indicative prices of ready-made grey water recycling systems
Product
Supplier Company
Capacity
(l)/per day
Price (€)*
Features
W-325
Brac Systems
325
1,245
Treatment system
for all grey water
GRS
ECO design Sustainable
Housing Greywater Recycling
& Irrigation Systems
Approx 300
1,538
Treatment system
for all grey water
-20 year warranty
AQUS
Arid Solutions Inc
N/a
217
Use your sink
water for toilet
flushing
* Prices do not include installation of grey water purification systems, extra plumbing work or any council permits you may require.
Rainwater Harvesting
A number of ecolodges, collect or “harvest” rain water in storage tanks for use in bathrooms and showers, such as the Zion
Country Lodge in Jamaica, or for watering plants such as tomatoes and other vegetables that are eaten raw like they do at Pentre
Bach Holiday Cottages in Wales. Rain water, which is naturally soft, is perfect for use in the washing machine, as it reduces the
amount of detergent and the build-up of limescale and so is used in various ecolodges for this purpose.
Latest Research and Conclusion
Latest research in grey water systems has focused on phosphorus-resistant plants that are suitable to clear grey water of
phosphorus deposits from common detergents. Using grey water as part of an integrated urban water management approach and
growing food crops is another subject of recent research. The growing importance of grey water reuse is perhaps reflected in the
recent (April 2007) grey water reuse proposal project for the installation of grey water reuse systems in 200 houses in Bathurst,
New South Wales. This April, Sydney Water is also promoting the installation of grey water household systems by making the
application procedure for Ku-ring-gai residents an easier and faster process.
Considering the imminent water shortage crisis, perhaps the most environmentally friendly measures that ecolodges should
adopt are not those of water reuse but those of water use minimisation. Similarly to the rise of preference for recyclable
products versus recycled, there is a growing need for us to reduce the utilisation of diminishing natural resources such as water,
both from an environmentally-friendly perspective as well as the all-concerning economic aspect. Predictably, the
