The development of grey water systems has come about to help alleviate problems with conventional sewage treatment – such as over burdened septic systems.
One advantage of a natural grey water system is to extract nutrients that would otherwise go to waste in a treatment facility. Other pluses are elimination of chemicals that would be used to treat grey water and the local benefits of water reclamation.
Where Does Greywater Come From
Greywater is water from sinks or showers. Waste water from toilets are excluded since this is considered blackwater; which contains organic material that harbors pathogens. Waste water from kitchen sinks is considered black-water in some municipalities as they contain organic material from food and grease. In other areas kitchen waste water is still considered greywater since food materials that enter the kitchen sink are looked upon as not containing pathogens. The safe route is to avoid any organic material.
Nutrients From Greywater
The biggest concern is the contamination of surface water from the nitrogen, phosphorus and potassium in greywater. Fortunately these agents of pollution are also the macro nutrients that plant life thrives on. A greywater system that utilizes plant life to soak up these nutrients serves a dual purpose: removing unwanted pollutants and contributing to the health and growth of a garden – a symbiotic relationship.
Sewage Treatment Versus Greywater Treatment
Greywater that is allowed to be treated in a sewage treatment plant undergoes chemical treatment to remove impurities. Once this happens the water is purified, but the problem is how to dispose of the chemicals used to treat the water. In a natural greywater system nutrients from the greywater can be utilized by plant life.
Where there is growth and decay there is also biological activity (worms, grubs, microbes) in the soil that will further break down greywater. As greywater is sifted down through rock, gravel and sediment it is further broken down and purified.
Benefits of Reclaimed Water
With the kind of growth that plants experience with greywater, the garden is the most obvious beneficiary from the extra nutrients. Along with all the extra growth composting is the natural next step in taking advantage of the extra organic material. The biological activity that occurs in the soil, such as worms and worm castings, serve to add to the fertility of the soil.
All the benefits derived from this process remains local – no infrastructure needed to transport it away to be treated and released even further away. Greywater that passes through this natural system will return to the water table waiting to be used again.