Studies of IDRC Supported Research on Greywater in ... - inwrdam

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to conserve water and reduce wastewater
discharge makes good sense.
Greywater contains oils, fats, detergents, soaps,
nutrients, salt and particles <strong>of</strong> food hair and
lint that can quickly clog a greywater irrigation
system. Whilst greywater from the kitchen
contributes least to the total greywater volume
it accounts for the bulk <strong>of</strong> fats, oils and
food particles, which are the primary components that cause this clogging. In contrast,
greywater from the bathroom and laundry accounts for the majority <strong>of</strong> the greywater
volume but generally contributes least to the components that clog an irrigation system
and requires only removal <strong>of</strong> suspended particles such as lint and hair.
Greywater contains contaminants which vary in their effects whether beneficial or
detrimental for irrigation <strong>of</strong> plants. These contaminants include nitrogen, phosphorous
and potassium, which in most cases are beneficial to plants. Greywater also generally
has a slightly alkaline pH making it preferable not to use greywater to irrigate acid
loving plants, unless pH is managed by digging soil conditioners such as peat or
compost into the soil.
Some strong household products such as caustic soda (drain cleaner) can be
detrimental to plant growth and when used the greywater can be diverted to the sewer
or where possible by simply disposing this wastewater to a fixture not connected to
the greywater system such as the toilet.
When greywater is being reused for garden irrigation users simply need to think
about what is being sent to the greywater system and not to use excessive amounts
<strong>of</strong> household cleaners and detergents to minimize any impact on plants and simply
because overuse is wasteful.
3.2 Why Use Greywater?
It is said that there is no such thing as “waste,” but just misplaced resources. Greywater
systems turn “wastewater” and its nutrients into useful resources. Why irrigate with
drinking water when most plants thrive on used water containing small bits <strong>of</strong>
compost?
Unlike many ecological stopgap measures, greywater use is part <strong>of</strong> the fundamental
solution to many ecological problems. It will probably remain an essentially unchanged
feature <strong>of</strong> ecological houses in the distant future. The benefits <strong>of</strong> greywater recycling
include: