“The most challenging aspect of installing a greywater system is the initial cost of the piping,” says Jeffrey Kling, a mechanical engineer with Gibbens, Drake, & Scott. “Not only are you piping water from the collection sites to the storage tank, you’re also using a separate, pressurized pipe to move the treated water back to its end destination.”
These design requirements make greywater an attractive option for new construction, where the piping can be accounted for from the onset. Other system components include:
- Storage tanks are needed to collect several thousand gallons of water.
- Particle filtration will catch debris with coarse, fine, and micron filters.
- Sanitization options address bacteria or toxins with agents such as chlorine or bromine, UV light, ozone, or copper-silver ionization.
For existing buildings, have a consultant or engineer evaluate whether it’s feasible for your current layout to accommodate the necessary harvesting elements. A major bathroom renovation may also offer the right timing to add separate piping, Kling notes.
Like any other building equipment, greywater recycling needs ongoing maintenance and monitoring to remain effective.
“No mechanical system runs by itself. Greywater systems should be diligently maintained by experienced and well-trained staff,” Benazzi recommends.
Flush with Savings
A utility bill can show you how many gallons are consumed, but do you know where in your building they’re used? You cannot efficiently collect and redirect water if you don’t know which areas are the highest generators.
To gain a better understanding of your building’s water performance, conduct an audit or use sensors and metering to better understand your gallon consumption. Use this data to calculate payback and document performance after the system is in place.
Greywater is also a scalable solution and you may decide to recycle only a portion of your facility’s domestic water, Kling adds. It may be more economical to gather water from just one set of bathrooms or a single floor of the building than to capture all of the qualified drains.
From there, quantify the system’s benefits. This can be expressed as a reduction in overall water consumption or as the percentage of greywater captured and repurposed.
“Water is only going to become more scarce and the increased costs are going to impact every commercial building,” Kling stresses. “If owners are serious about occupying a building for 50 to 80 years, they’ll need to start using these water conservation techniques. Otherwise it will become too much of a burden to operate the building and it won’t be the investment it once was.”
Jennie Morton firstname.lastname@example.org is associate editor for BUILDINGS.