Septage or septic tank sludge refers to the partially treated sludge stored in a septic tank or (less commonly) in a pit latrine. It is one type of fecal sludge. Septage is a by-product from the pretreatment of household wastewater in a septic tank where it accumulates over time. Septage is pumped out of a septic tank or onsite sewage facility with a vacuum truck. The septic tanks can be residential or non-residential. Non-residential sources can include wastewater from commercial/industrial development, grease interceptor as well as other sources such as portable toilet, RV, and boat waste.