Section R. 325.423 - Minimum standards for septic tank privy or septic toiletRule 3.
(1) The tank should be located at least 50 feet from any well or other source of groundwater supply and upon ground sloping away from the water supply. No tank shall be located less than 2 feet from any lot or alley line or less than 25 feet from any lake or stream.(2) The tank shall be constructed of an impervious material and be watertight. The depth below the outlet pipe shall be not less than 30 inches. When constructed of concrete the side walls, top and bottom shall be of a mixture and thickness which will insure a dense, watertight structure. Sufficient reinforcement shall be used to prevent cracking. When constructed of metal, Armco ingot iron or other rust-resisting material not less than 12 gauge shall be used. All metal surfaces inside and outside shall be thoroughly coated with a good quality asphalt base material. All tanks shall be provided with an outside opening, not less than 12 inches in diameter, fitted with a tight cover, to permit inspection and cleaning. The outlet of all tanks shall be so constructed as to prevent solid material passing into the discharge pipe. Tanks should be filled with water before being put into operation and after each cleaning.(3) A drop tube, securely fastened to the toilet bowl and to the tank, shall extend into the tank but not more than 2 inches below the water line. A vitreous china toilet bowl with seat and seat cover securely hinged should be used.(4) A ventilating pipe connected to the bowl and extending above all parts of the building shall be installed.(5) Cast-iron soil pipe shall be leaded or bonded to the tank and extend not less than 10 feet from the building where it may be connected to the disposal tile. Disposal tile should be laid so that a 12-inch earth cover is provided. Under no condition shall the tile line be laid below the groundwater level.Mich. Admin. Code R. 325.423
1944 AC; 1944 ACS 7; 1954 AC; 1979 AC