By: Mary Campbell, Extension Director and Urban Sustainability Agent
As we try to reduce our carbon footprint water conservation can be an important factor. It takes a lot of energy to treat and move water through our community. The more water we use, the more energy that is used. If you have maximized your water conservation practices like fixing all leaks, filling your dishwasher before using and taking shorter showers; and if you have already installed low flow toilets, low flow shower heads, a water efficient washing machine and micro-irrigation, you may be wondering how you can reduce your water use even further.
Reusing gray water from showers, bath tubs, clothes washing, and some sinks for flushing toilets and irrigating non-edible portions of the landscape is a way to reduce the need for new sources of fresh water and reduce reliance on groundwater resources.
There are several requirements for gray water systems for flushing toilets in Florida. Distribution piping must be clearly identified as containing non-potable water by pipe color or with metal tags. Gray water must be filtered, disinfected, and dyed. Gray water storage reservoirs must be appropriately sized and must have a make-up potable water supply. Storage reservoirs must also have drains and overflow pipes which must be indirectly connected to the sanitary drainage system.
There are four main components of a gray water system for flushing toilets:
• Filter system
• Storage reservoir
• Disinfection unit
• Coloring dye injection unit
Prior to entering the gray water storage reservoir, gray water must be filtered using an approved media, sand, or diatomaceous earth filter . Gray water storage reservoirs must be constructed from durable, non-absorbent, and corrosive-resistant material. Storage reservoirs must be closed, gas-tight, and must have access openings that allow for inspection and cleaning. Storage reservoirs must be equipped with an overflow connection to a sanitary drainage system. Gray water used for flushing of toilets must be disinfected prior to use by an approved method using one or more disinfectants such as chlorine, iodine, or ozone (Florida Building Code, 2007).
While reusing gray water has the potential to substantially reduce the use of fresh water, there are several barriers which may impede the adoption of residential gray water reuse in Florida and elsewhere. These include:
• System cost
• Knowledge and experience of contractors and local officials
• Sufficient and consistent codes and guidelines
• Homeowner acceptance
• Limited permitted uses
It is likely that policy makers will be more receptive to expanding gray water reuse in the future as pressures increase on finite fresh water resources.