What do a running faucet, a kitchen sink, and a load of laundry have in common? They all produce greywater, one of the most underutilized resources in your building.
Greywater recycling offers a way to repurpose discarded domestic water and go beyond low-flow fixtures and drought-tolerant landscaping. You’ve already paid for the water – why not use it again?
The Case for Greywater
Greywater reclamation is often pushed by building owners who adopt a long-term view of sustainability. A lower water bill is a worthy goal, but the bigger picture lies within your community.
Extracting water from local aquifers can have negative impacts on the ecosystem (Lake Mead, for example) and extreme weather conditions in recent years have generated a rash of droughts. Domestic water treatment is also an energy-intensive process that uses chemical disinfectants, among other measures, to clean water.
Any opportunity to adopt water conservation methods such as greywater recycling will benefit your building performance goals and the future stability of your region’s water supply.
Most facilities managers are familiar with stormwater, which is harvested after a rain. Greywater, however, is reclaimed from bathroom and kitchen sinks, laundry machines, and shower drains.
“Because greywater has soap, detergent, or biological material in it, you need chlorine or bromine to purify it,” says Bob Benazzi, a retired consultant for Jaros, Baum & Bolles (JB&B) Consulting Engineers. “Greywater should also be filtered before it’s released into your pipes.”
Note that water from toilets is off limits. Anything that comes into contact with human or animal waste is considered blackwater and requires the same purification precautions as a sewage treatment plant. Some facilities may classify shower and bathing water as a greywater option, whereas others feel the level of bacteria is too high, Benazzi explains.
Treated greywater is commonly recycled in restrooms to flush toilets and urinals and for drip irrigation – applications where it couldn’t be unintentionally breathed as an aerosol.
With added filtration measures, greywater can also be used for regular irrigation, sidewalk washing, and mechanical evaporation.