 some other dedicated system. The grey water system can employ a conventional septic tank and drain field system as well, but is usu- ally designed to enable reuse of the grey water. The most common use of grey water is for irrigation. The tech- niques described in the section on land application are amenable to grey water use. Also the same restrictions, such as provision for winter disposal, apply. For summer homes, a grey water system can be used without regard to alternative disposal means. Another use for grey water is to recycle to the toilet(s). Even for this use, however, the grey water must be treated and disinfected. A note of caution is due. Use of a grey water system has been a symbol of environmental consciousness. Indeed, the recycling of wastewater is commendable now and will eventually be mandatory. Many persons have, with the best of intentions, installed "grey water systems" with unfortunate results. Confident anticipation has turned to patient redesign and experimentation, followed by disillu- sionment and abandonment of the whole effort (and the associated investment). There is a whole series of disasters waiting to visit the poorly planned grey water system. There are the generic problems such as nonconformance with local codes and foul odors, and there are the system-specific problem such as filter clogging and sub- merged disposal fields. Virtually all of these problems can be cir- cumvented by matching the proper design to the intended applica- tion. Process The separation of black and grey waters occurs through the instal- lation of separate plumbing. This means that a retrofit grey water system varies from easily done to impossible. Where access to the plumbing is available (where a basement or crawl space exists), a cost-effective alternative to redirecting all the existing piping is to tap the bathtub/shower drains and sink drains of a bathroom on the side of the house where the grey water septic tank will be located. Grey water should always be treated before discharge, and the LOW-IM