Recycling Systems

Greywater is wastewater generated by daily activities that doesn’t include water contaminated by human wastes like sewage. Unlike the blackwater that comes from a toilet, greywater has a minimum of contaminants, mostly household cleaners and food residue, and is produced by laundry machines, dishwashers and showers. Because greywater is far cleaner than blackwater, it requires far less intensive purifying techniques to reclaim it for additional use, making it an appealing target for recycling efforts. Greywater recycling systems come in a plethora of different forms, the basic types of which will be outlined below.

All greywater recycling systems rely on sequestering the various sources of wastewater produced by a house and separating the sources that contain greywater. This is done through plumbing systems that prevent the mixture of a home’s greywater with wastewater from toilets or other blackwater sources. Just separating the water allows a more nuanced water treatment strategy to be employed and reduces the load on water purification facilities. But most of the benefits from greywater recycling are based on on-site recycling.

Hard vs. Soft

Greywater recycling comes in two major forms: treated and untreated. Untreated greywater recycling systems are generally far simpler than their treated relatives though they are subject to several restrictions on the lengths of time they can be stored and the uses the resulting water can be put to. Untreated water purification systems are sometimes called ‘diversion’ systems. Diversion systems take the sequestered greywater and store it for irrigation or other purposes where potability is not necessary. The legal questions surrounding the installation of greywater recycling are heavily dependent on the location where the system is to be installed, though areas with water shortages often have special legal provisions for diversion systems.

For applications requiring potability, greywater recycling systems are designed with water treatment components designed to cleanse the impurities from the water and sterilize any bacterial contaminants. These systems come in two theoretical types: hard and soft. Hard recycling systems are only in use for larger scale recycling operations and they rely one or more mechanical or chemical processes to render the greywater clean. Chemical treatments and distillation processes are the most common types of hard recycling systems, but there are no commercially available systems rely on these techniques.

Soft water treatment is the default method of water purification for home filtration systems designed to recycle greywater. Soft techniques rely on techniques inspired by the natural water cycle, using biological or passive processes to render the water safe for consumption. These systems mimic or exaggerate the natural processes that clean water, such as various natural filtration systems, ecological systems like synthetic wetlands and various biologically inspired filters or bio-active systems.

Common Examples of Soft Recycling Elements

The most common soft recycling systems are designed to mimic the water cycle’s filtration system by copying geographical configurations that are responsible for the creation of naturally occurring clean water. Water diverted from the house’s sequestered water system is split into gray and blackwater. Blackwater is flushed out of the houses system into whatever sewage system is in place, while the greywater is pumped through one or more of the various filtration methods.

To ensure that the resulting water is properly purified, most greywater recycling systems rely on more than one of the filtration methods to offer both a primary and secondary (and in certain cases, tertiary) stages. The exact nature of a given water filtration and treatment system depends on a large number of local factors like the environment and climate, as well as local legal rules.