Sally Furniss
Well-known member
WHY IRRIGATE WITH GREYWATER (GRAYWATER)
Greywater comes from the bathroom, laundry and kitchen. Whilst greywater does not contain toilet waste it nevertheless generally contains the same pathogenic micro-organisms (though in much lower numbers) just from washing your hands, bathing and washing soiled clothing. Therefore, health authorities recommend caution when reusing greywater. The best means of addressing their concerns, without use of expensive and often un-reliable treatment and disinfection technologies is simply to irrigate greywater below the ground surface to avoid un-necessary human contact.
Whilst greywater will always contain some micro-organisms the health hazards from a multi dwellintg greywater source are significantly greater than from a single dwelling greywater source. This is because within a single dwelling setting inhabitants already have intimate exposure to the same greywater whilst bathing and washing and essentially to their existing family unit's reservoir of micro-organisms, whereas exposure to greywater from multi dwelling sources has potential to expose an individual to micro-organisms not already present within their family unit and there a greater potential for spread of disease.
Greywater contains traces of oils, fats, detergents, soaps, nutrients, salt and particles of food hair and lint etc, that can quickly clog a greywater subsurface irrigation system. Whilst greywater from the kitchen contributes least to the total greywater volume it accounts for the bulk of fats, oils and food particles, which are the primary components that cause this cloging. In contrast, greywater from the bathroom and laundry account for the majority of the greywater stream but generally contribute little of the components that cause clogging and therefore generally requires only removal of suspended particles such as lint and hair. For this reason most states only consider greywater from the laundry and bathroom as suitable for diversion for irrigation.
GREYWATER AND PLANTS
Greywater contains contaminants, which vary in their effect from beneficial to detrimental for irrigation of plants. These contaminants include nitrogen, phosphorous and potassium, which in most cases are beneficial to plants, except for a small number of native plants that have a unique low phosphorous or nutrient tolerance from having evolved and developed in marginal nutrient depleted soils. Greywater also generally has a slightly alkaline pH making it preferable not to use greywater to irrigate acid loving plants, unless the pH is managed, by digging soil conditioners such as peat or compost into the soil. Suitable plants and soil conditioners should be discussed with your local gardening centre.
Some laundry detergents and bleach will results in greywater with increased levels of sodium salts that can be detrimental to plant growth. Therefore, it is preferable to use products with low sodium levels, as found in most but not all liquid laundry detergents. Some strong household products such as caustic soda (drain cleaner) can be detrimental to plant growth and when used the greywater should be diverted to the sewer or septic tank.
When greywater is being reused for garden irrigation users simply need to think about what is being sent to the garden via their greywater system and to not use excessive amounts of household cleaners and detergents so as to minimise any impact on plants and simply because overuse is wasteful.
http://www.greywatersaver.com/greywaterreuse.htm
Greywater comes from the bathroom, laundry and kitchen. Whilst greywater does not contain toilet waste it nevertheless generally contains the same pathogenic micro-organisms (though in much lower numbers) just from washing your hands, bathing and washing soiled clothing. Therefore, health authorities recommend caution when reusing greywater. The best means of addressing their concerns, without use of expensive and often un-reliable treatment and disinfection technologies is simply to irrigate greywater below the ground surface to avoid un-necessary human contact.
Whilst greywater will always contain some micro-organisms the health hazards from a multi dwellintg greywater source are significantly greater than from a single dwelling greywater source. This is because within a single dwelling setting inhabitants already have intimate exposure to the same greywater whilst bathing and washing and essentially to their existing family unit's reservoir of micro-organisms, whereas exposure to greywater from multi dwelling sources has potential to expose an individual to micro-organisms not already present within their family unit and there a greater potential for spread of disease.
Greywater contains traces of oils, fats, detergents, soaps, nutrients, salt and particles of food hair and lint etc, that can quickly clog a greywater subsurface irrigation system. Whilst greywater from the kitchen contributes least to the total greywater volume it accounts for the bulk of fats, oils and food particles, which are the primary components that cause this cloging. In contrast, greywater from the bathroom and laundry account for the majority of the greywater stream but generally contribute little of the components that cause clogging and therefore generally requires only removal of suspended particles such as lint and hair. For this reason most states only consider greywater from the laundry and bathroom as suitable for diversion for irrigation.
GREYWATER AND PLANTS
Greywater contains contaminants, which vary in their effect from beneficial to detrimental for irrigation of plants. These contaminants include nitrogen, phosphorous and potassium, which in most cases are beneficial to plants, except for a small number of native plants that have a unique low phosphorous or nutrient tolerance from having evolved and developed in marginal nutrient depleted soils. Greywater also generally has a slightly alkaline pH making it preferable not to use greywater to irrigate acid loving plants, unless the pH is managed, by digging soil conditioners such as peat or compost into the soil. Suitable plants and soil conditioners should be discussed with your local gardening centre.
Some laundry detergents and bleach will results in greywater with increased levels of sodium salts that can be detrimental to plant growth. Therefore, it is preferable to use products with low sodium levels, as found in most but not all liquid laundry detergents. Some strong household products such as caustic soda (drain cleaner) can be detrimental to plant growth and when used the greywater should be diverted to the sewer or septic tank.
When greywater is being reused for garden irrigation users simply need to think about what is being sent to the garden via their greywater system and to not use excessive amounts of household cleaners and detergents so as to minimise any impact on plants and simply because overuse is wasteful.
http://www.greywatersaver.com/greywaterreuse.htm
