Grey water is water that has been used for washing (bath and shower water, and water from washing machines etc.) but which does not contain any sewage or food. Homes with grey water recycling systems typically have two separate plumbing systems: one to carry black water away from toilets and kitchen garburator, and provide potable water to kitchen and bathroom faucets; and one to carry grey water to a tank for treatment, then deliver it to toilets and perhaps outside taps.
Benefits of grey water recycling
Grey water reclamation has a number of benefits:
- It saves water. Freed and Daum report that homes with a grey water recycling system will enjoy 30% to 60% lower water costs than other homes.
- Because less water is used, it puts less strain on the environment, wastewater treatment facilities, and private wells and septic systems.
- When used for irrigating plants, it provides some fertilizer.
Grey water treatment
Grey water collected in a tank can’t be recycled without some treatment: the water must be cleaned and disinfected before it can be used for flushing toilets and other purposes. Depending on the system design, the water may be filtered and/or treated with chemicals to ensure minimum standards of cleanliness so that this water can be used to make ice cubes. You can use it to wash your dishes too.
Concerns about grey water recycling arise from the likelihood of discoloration or other poor appearance, odor, and the possibility of the presence of disease causing organisms. Some jurisdictions do not yet allow grey water systems; some don’t allow any use of grey water other than flushing of toilets and urinals, and some permit wider use including clothes washing and garden irrigation.
Disadvantages of grey water systems
Water reclamation of this type does require greater initial expense to install the system, and ongoing attention and maintenance:
- Great care must be taken to ensure that black water, grey water, and potable water never mix in the household plumbing.
- Environmentally unfriendly cleaning products and chemicals must not go down the drain and contaminate the grey water.
- Regular maintenance of filters may be required.
- Water in the grey water system must be monitored for appearance, and tested regularly for the presence of microorganisms and chlorine (if chlorine is used as the disinfectant).
Grey water recycling is not yet accepted by everyone: health and esthetic concerns remain. As environmental consciousness and grey water recycling become more prevalent, however, both objections and perceived disadvantages are likely to become less compelling.