This specification covers monolithicor sectional precast concrete septic tanks. The following materials shall be used for manufacturing concrete septic tank: cement, aggregates, water, admixtures, steel reinforcement, concrete mixtures, forms, concrete placement, fibers, and sealants. The precast concrete sections shall be cured. Structural design of the septic tanks shall be by calculation or by performance. Concrete strength, reinforcing steel placement, and openings shall also be considered in the design. The physical design requirements include: capacity, shape, compartments, influent and effluent pipes, baffles and outlet devices, and openings in top slab. The following tests shall also be done: proof testing, leakage testing, vacuum testing, and water-pressure testing.