12VAC5-610-810: Anaerobic biological systems

Septic tanks are the most commonly used pretreatment systems and under normal circumstances are the most inexpensive units that give acceptable results with a minimum of maintenance.

The preferred material for use in constructing septic tanks is concrete. Other materials may be considered on a case-by-case basis. All materials must be resistant to corrosion, both chemical and electrolytic, and must have sufficient structural strength to contain sewage and resist lateral compressive and bearing loads.