Graywater: reusing water where treated water is unnecessary
It seems that every year, some place in the US suffers tremendous flooding at the same time some other place suffers severe drought or worse. Wouldn’t it be nice to be able to move excess water from floods to dry areas that need it? Short of that, graywater–waste water recycling–can at least mitigate water shortages.
What is graywater? It’s used water: any water from sinks, bathtubs, showers, washing machines–in short, anything but toilets, washing diapers and in some jurisdictions dishwater. That definition includes up to 80% of household wastewater.
Graywater can be used to flush toilets, to irrigate the yard or garden, or perhaps wash the car if you must do that at home. (Commercial car washes recycle the water they use. If you do it at home, all that water just goes down the drain.) Theoretically, at least, using gray water offers numerous environmental advantages.
- It uses less fresh water from the treatment plant, which, apart from the worst drought conditions, is the only real water shortage people face in this country.
- It puts less strain on wastewater treatment plants and septic tanks.
- Topsoil treats graywater much more effectively than any treatment plant could.
- Using graywater for irrigation does not use either the energy or the chemicals required at the wastewater treatment plant.
- Applying graywater to the soil recharges groundwater. Effluent from the wastewater treatment plant gets discharged into streams and immediately leaves the area.
- Plants get not only water, but nutrients from the graywater that would otherwise be wasted. The quantity of sludge produced at the wastewater treatment plant is, with current technology, a waste disposal problem and not a usable resource.
- It presents a fundamental solution to numerous environmental problems; it is not a stopgap.
