nks can overcome almost any site limita- tion. All waste discharged from the home is retained. As the con- tainer becomes full, a septic tank pumper or truck must be employed to haul the contents away. These hauling charges may be prohibitive. Sealed vaults are most often used to serve seasonal dwellings in areas unsuitable for installation of drain fields. Grey water disposal systems with no discharge of black water (toilet and garbage disposal wastes) can significantly reduce the volume of discharge and the associated drain field area requirements. Reten- tion of the black wastes, for example, in a sealed vault or compost- ing toilet, also significantly reduces the amount of pollutants intro- duced into the environment. Some states may allow credit for ground water or bedrock clearance for this reduction. Water conservation is a good practice. Less water entering a liquid waste treatment unit and disposal system can postpone or eliminate system failures. The reduced amount of water may allow a reduc- tion in the size and, therefore, the cost of the system. This may be particularly beneficial when practiced in combination with the use of the more expensive alternative systems. Electro-osmosis is a new technological development applied to liq- uid waste disposal. It is a disposal system which is reported to overcome limitations of slow percolation rates by means of inducing an electric current across the drain field using buried minerals. More information on this disposal method can be obtained from sources listed in the bibliography at the end of the book. As it is still in the ONSITE WASTEWATER DISPOSAL Figure 3.17 "Stacked" pipes. early stages of development and demonstration and is not a proven technology, it will not be described in this book. SYSTEM LOCATION Once the types of liquid waste treatment and disposal systems best suited to a particular site and use have been selected, the most suitable location for the units should be determined. It is always best to plan the location of these units in conjunctio