Plumb green with graywater

Plumb green with graywater

By Georg Efird on 03/16/2009

Graywater is not a new term to many of us. It is water that has been used in the kitchen sink, washing machine, bathroom lavatories, showers, tubs and condensation systems. The amount of graywater available varies from household to household depending on the amount of water use by humans.

Blackwater, on the other hand, accumulates in any receptor that receives human waste, such as water closets, urinals and bidets.

To reap the benefits of reclaiming graywater, all blackwater drain, waste and vent systems must be piped separately from graywater drains. This procedure requires a licensed plumber and preferably one who is an accredited green plumber with experience in graywater reclamation and water conservation.

The use of graywater has been around for decades, but most local codes limit or do not allow graywater use. There are many different variables that determine the type of graywater system to be used.

The system familiar to most people is one that routes kitchen-sink and washing-machine wastewater outside the home separately from the sewer line. Typically, the graywater waste line is piped 2 feet underground into a bed of dry gravel. This system was designed only to reduce the strain on the septic leach field. Septic systems were sized by accounting for this system. If you have ever seen a kitchen sink or washing machine piped underground, it was probably this type of graywater system. This system is no longer legal in the state of North Carolina.

Widely used in the Western part of the U.S., another approach is one in which all graywater pipes are combined, but separate from blackwater pipes. Once graywater reaches the outside of the home, it is piped into zones that feed different areas of landscape, garden, fruit trees and other needs. The piping is sized according to the amount of graywater needed for irrigation. Every garden zone has a zone valve to regulate flow. Every fixture inside the home has a 3-way valve that can divert the graywater back to the sewer drain line when the gardens/landscapes are sufficiently hydrated. During times of drought or hot summer—when gardens need water the most—the valve can be set to stay on graywater. This method of reusing graywater is also illegal in N.C.

A third type of graywater reclamation system has been legal in N.C. since 2006. It is a current legal plumbing code in the 2008 International Code Council and International Plumbing Code book, volume 1, plumbing code. There are very strict guidelines to follow. Here are a few of them:

  • No less than a 50-gallon tank may be used. 
  • No more than a 120-gallon tank may be used. 
  • Vent, drain and waste must not be intermingled. 
  • There must be a separate water supply line from the graywater supply line. 
  • All graywater piping must be labeled as unsuitable for drinking. 
  • Reclaimed graywater can only be used for water closet and urinal flushing. 
  • Chlorine and green dye are required.

In N.C., all graywater systems must be approved by code officials prior to installation per job site. The officials you need to speak with are Mark Case, City of Asheville, or Matt Stone, Buncombe County. Most counties in N.C. are in favor of this system.

There are also graywater reclamation systems that can be installed under the kitchen or bathroom sink. These are smaller versions of the systems explained above, in which the pipes do not have to be rerouted.

The price of a graywater reclamation system varies depending on the amount of fixtures from which graywater is reused. For a whole-house system that uses graywater to flush water closets, bidets and urinals, you are looking at prices ranging from $1,300 to $1,700 per bathroom. An under-sink type of graywater reclamation system costs approximately $400 to $700 to install. These are only estimates, as all buildings and plumbing systems are different.

In conclusion, a graywater system will save approximately 40 percent of your freshwater use, thus reducing strain on our ever-decreasing water supply and your water footprint.

Georg Efird is president and owner of A2Z Plumbing & Gas Piping Inc.