A thorough site evaluation must be conducted in order to determine the appropriate level of pretreatment prior to final onsite subsurface disposal of the greywater portion of the wastestream. Septic tanks can provide for only primary levels of treatment. Odors may result from composting toilet units if anaerobic conditions occur. The composted product must be tested for adequate pathogen reduction, and to ensure that concentrations of metals and other regulated parameters are below accepted limits. Energy Consumption Septic tanks do not require power consumption.
Wastewater drains by gravity from the house to the tank.
Energy consumption for composting toilet units is estimated at 2 to 3 KWH per day per unit, with each serving an average of two persons on a regular basis. Costs for maintaining composting toilet units are based upon the composted product being transported to a facility which is permitted to receive municipal sludge and septage. Aesthetic Considerations Septic tanks are buried below grade, and usually do not have significant visual impacts on the site. Composting toilets may not be desirable to some residents, for varying reasons. The composted residuals must be periodically removed from these units.