Graywater Recycling System

Domestic graywater systems collect used water from non-toilet fixtures, such as sinks, showers and washing machines, and reuse it for other applications.

Some graywater systems treat the water before it is reused, and others do not. If treated, it may be used for washing. If untreated, it is typically used for non-potable applications, such as irrigation and toilet flushing. Recycled graywater is not safe to drink.

A graywater recycling system can help reduce your water bill, because you are using the same water more than once in your home. Graywater recycling systems are considered green because they reduce the use of potable water use for non-potable applications, which lessens impacts on rivers and aquifers. It can have additional benefits, such as reclamation of nutrients (which is helpful for irrigation) and smaller impact on septic systems.

Installing a graywater recycling system typically requires an experienced installer (or plumber).

Free LEED GA Practice ExamExamples of Graywater Systems

For example, the four following graywater systems are currently available on the market.

1. Aqua2use

Matala Water Technology, a Taiwan-based company, offers a graywater treatment system that can save up to 30 gallons of water per person per day, or the equivalent of 40,000 gallons annually for a family of four.

It collects used water from the shower, dishwasher and laundry machine, and treats it with biological and mechanical filters. Then, it disinfects it with UV-C, and it can be reused for flushing the toilet, laundry washing, and watering the landscape.

In 2012, it was selected by BuildingGreen as one of the top 10 green building products of the year.

2. Sloan AQUS Water Reuse System

The AQUS Water Reuse System from Sloan is specifically used for bathroom applications. Graywater is collected from the sink from handwashing, then treated by a sanitizer and kept under the sink in a storage container. The reservoir is connected to the toilet, so that water is then reused for flushing. The system is compatible with many types of toilets, including models from Kohler, TOTO, Western and American Standard.

The AQUS, which requires annual maintenance, can save up to 6000 gallons of water per year.

Sustainable Industries also chose the AQUS as one of the top 10 green building products, but in 2010.

3. Clivus Multrum

Clivus Multrum, founded in 1962 by the Swedish the inventor of composting toilets, offers a number of greywater systems, which is custom designs for site-specific conditions. For example, one system collects greywater from all of the non-toilet fixtures in the building and pumps it outside to an irrigation system. Most of the company’s systems do not treat the water, but rather channel it directly to landscaping, where the plants make use of the water’s nutrients.

4. Aquacell

Phoenix-based Aquacell Recycling Solutions is unique in that it offers both graywater and blackwater treatment systems. Available for residential and commercial applications, they treat used water for non-potable applications, like irrigation, clothes washing and toilet flushing.

Aquacell’s G Series is a graywater recycling system, which collects water from baths, sinks, showers, and washing machines, but not toilets. It treats the water with aerobic screening, biological treatment, ultrafiltration, ultraviolet disinfection, and chlorination. Then, it can be stored and reused for non-potable applications, and can reduce water use for those actitivies by 30-50%.

The company’s S Series is a blackwater recycling system, which treats water from toilets that have come in contact with human waste. The system, which can be installed in a new construction project or as a retrofit, uses treatment that involves screening, biological treatment, ultrafiltration, ultraviolet disinfection, TDS and nutrient removal, and chlorination. Once treated, it can be re-used for watering the landscape, toilet flushing and washing clothes.

If the S Series is combined with a graywater system, it can reduce potable water use in the building by up to 90%.

Both the G Series and S Series are installed by Phoenix, a Louisville, Kentucky-based company. The company will remotely monitor the systems 24/7.

Graywater and LEED

Graywater systems could contribute to LEED in the Water Efficiency credit category of the LEED for New Construction (NC) rating system. These products could specifically contribute to the following credits in LEED NC:

• Water Efficiency (WE) Prerequisite 1: Water Use Reduction (0 points)
This prerequisite requires that the LEED project use 20% less water than the baseline calculation. Since graywater can be reused, such as for flushing toilets, treatment systems could contribute to this prerequisite.

• WE Credit 1: Water Efficient Landscaping (2-4 points)
This credit requires a 50% reduction (2 points) or 100% elimination (4 points) of potable water used for irrigation. Since some systems reuse graywater for irrigation, they could contribute to this credit.

• WE Credit 2: Innovative Wastewater Technologies (2 points)
This credit awards points for cutting potable water use for sewage conveyance in half, or by treating half of the wastewater on-site to tertiary standards. Graywater or blackwater treatment systems could contribute to this credit.

•WE Credit 3: Water Use Reduction (2-4 points)
This credit is the same as WE Prerequisite 1, except it requires higher levels of water conservation. Projects can earn 2 points for 30% water reduction, 3 points for 35%, or 4 points for 40%.

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