Septic tanks should be pumped at an average frequency of 2 to 5 years, in order to prevent too much sludge and solids build-up. The pumping frequency for septic tanks receiving greywater should be less than for those receiving combined wastes. N ratios, moisture content, and aerobic conditions. The moisture and temperature of the compost must be properly maintained. 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.