Manufactured Greywater Systems
There are several manufactured greywater systems on the market in the US and Canada, and many more in Australia. They all have the same basic concept: collect the greywater in a temporary storage tank, filter and maybe disinfect it, then pump it out for toilet flushing or landscape irrigation.
In most single family homes with yards, using greywater directly for irrigation provides the greatest water savings for the least cost, embodied energy, energy use, and maintenance. In multi-family or commercial buildings with little irrigation need, reusing greywater to flush toilets can save significant amounts of water. Manufactured systems require regular maintenance, and a 6-month study in the UK found that several systems installed in private residences failed because their users didn’t maintain them.
Manufactured Greywater Systems for Irrigation
Manual Cleaned Filter Systems
Some manufactured greywater systems rely on a person to clean the filter. These systems are more prone to failure due to lack of maintenance. If you are considering a system that requires manual filter cleaning get a maintenance contract with the installer to upkeep the filter, or install a system with a self-cleaning filter instead.
These systems are currently on the market and have a manually cleaned filter:
Aqua2Use: This system is housed in a small plastic box (about 2′ x 2′ x 1′) with a series of filters inside and a low powered pump after the filters. The filters require manual cleaning. When they clog greywater can’t flow through them and it instead flows to the sewer/septic. The filtered greywater from this system isn’t clean enough for a drip irrigation system, it can be used with 1/4 inch outlets, or additional the system can include additional filters (not part of the Aqua2Use system) for smaller drip emitters. Users report problems with the pump and other technical difficulties, like the float switch getting hung up inside the box and burning out pump.
GreyFlow G-Flow: The Australian company Advanced Waste Water Systems (AWWS) makes several greywater irrigation systems. G-Flow is their most basic system with a filter that requires manual cleaning.
Gray-It is a residential greywater system made by the Israeli company Green Solutions. It has two filters that require manual cleaning, and sends filtered greywater into a drip irrigation system. A controller monitors how much greywater is flowing through the system, if there isn’t enough the system brings in potable water to complete the irrigation cycle.
Self-Cleaning Filter Systems
More sophisticated greywater systems employ a self-cleaning mechanism for the filter. The most common way to clean the filter is to backflush it with pressurized tap water. This works well but adds additional regulatory concern and oversight due to the potential for a “cross-connection,” and results in higher permit fees. One system on the market, GreyFlow Plug-in-Play, uses compressed air to clean the filter, resulting in a lower cost system with less regulatory concerns, making permitting easier.
These systems are currently on the market and have a self-cleaning filter.
IrriGRAY: The new IrriGRAY system is made by the company WaterReNu (note that the previous IrriGRAY used a manually cleaned filter and has now been discontinued). The IrriGRAY system pumps filtered greywater into a drip irrigation system and can be monitored remotely from a smart phone or computer.
Grey Flow PS Plug-N-Play: Made by the Australian company Advanced Waste Water Systems (AWWS), greywater flows into the system, through a filter, and is pumped out into the greywater compatible drip irrigation system. On a regular basis the system automatically cleans the filter by blasting compressed air up through the filter to dislodging dirt and debris, while incoming greywater washes it to the sewer. Since there is no potable water connection, just compressed air and greywater to clean the filter, the system is simpler to install with lower permitting fees than other types of self-cleaning filter systems.
Nexus E-Water (see below) is designed for irrigation and toilet flushing. It has remote monitoring capabilities.
ReWater system has been on the marker for over 20 years, far longer than any other system. It consists of a self-cleaning sand filter (with potable water to backflush it), irrigation controllers, and greywater-compatible drip irrigation system.
Manufactured Greywater Systems for Toilet Flushing
In general, toilet-flushing greywater systems usually require frequent maintenance, manual cleaning of filters, and chemical disinfectant to prevent odors in the bathroom. They also tend to be relatively complicated, and it’s critical that they be designed and installed properly. If you are considering such a system try to find people to talk to who’ve had the systems installed in their homes for at least a year, and be sure to find out the maintenance requirements of the system. Consider maintenance contact with the installer (if you can afford it) for any system that requires more than annual maintenance.
Nexus E-Water is a home water and energy recycling system. It is NSF-350 certified, which means it will be easier to obtain permits for it in states like California. The system treats greywater for use in either toilets or for irrigation (no irrigation components are included in the system- you have to design/purchase that portion separately). The system also harvests the heat energy in greywater using conventional heat pump technology. They expect to recycle 3 out of every 4 watts of energy needed to heat water in the home.
Water Legacy was a company with a system similar to Brac’s that uses hydrogen peroxide and UV as disinfectant instead of chlorine. They were made to only be used with shower greywater, and have an inlet filter that requires regular cleaning. The company is no longer in business.
Performance of toilet flushing systems
Kohler conducted a study on residential greywater systems and how they impact toilets over time. You can download a presentation of the study here. They installed four different types of systems that use shower water to flush toilets and tested them for one year. Studies and system users report that lower-cost systems ($3,000–$5,000) have maintenance issues, while the better-functioning ones cost a lot ($8,000–$9,000).