PACT SYSTEMS most cost-effective means of treatment is with a septic tank. Although, theoretically, a septic tank of several hundred gallon capacity should suffice for grey water treatment (provide a two-day retention time), a standard-sized precast tank won't be much more expensive and will afford some extra protection for your disposal system. A considerable amount of extra protection for the drain field and reduction of maintenance on the grey water system is achieved if the kitchen sink is not plumbed into the grey water system. A gar- bage disposal will stress even a conventional system, and the grease washed down the kitchen sink readily clogs filters and generates odors. The longer the grey water sits in the tank, the cooler it becomes, and the more grease solidifies and floats to the top. This is grease that won't enter and clog the disposal system. Also, more time is available to allow the fine solid material to sink to the bottom of the tank. Filters have been suggested as an alternative to septic tanks for grey water treatment. The maintenance required on a filter used for this purpose is SO extensive as to dissuade all but the dedicated dabblers. The place for a filter is after the septic tank. Whether or not a filter is needed depends on the disposal or reuse chosen. If aboveground irrigation is chosen and disinfection is needed, use of a filter is advisable. Solids will use up chlorine and bromine in very short order. If a drip irrigation system is to be used, the addition of a filter is virtually mandatory to prevent clogging of the emitters. Another benefit of filtration is that it can add oxygen to the grey water, which promotes digestion of the organic matter and reduces the potential for odors. A question often arises as to whether or not to disinfect the grey water prior to reuse. Notwithstanding ordinances and regulations, the answer should be based on common sense. Grey water can and sometimes does provide a comfortable and nutritious medium for disease-causing organisms, SO don't provide a 