DESIGN OF THE SEPTIC TANK BASED ON IS: 2470

DESIGN OF SEPTIC TANK.:-- According to IS :2470 septic tanks shall have minimum width of 75 cm minimum depth of one meter below the water level and a minimum liquid capacity of one cubic meter The length of the tanks shall be two to four times the width .The size of the septic tank is based on the number of users and the amount of dilution water in the sewage. It is considered that as long as the dilution per head is more than 25 litres and less than 180 litters, a septic tank having a content of about 0.071 cu.m per user will do the work required.The largest practical size for a single unit is considered to be 22mt long and 2.7 mt wide and 2.1 mts high size of the tank which is sufficient for 2500 users .A small septic tank can also be made adjoining the privy wall a water seal latrine instead of the pit where a vent pipe should be provided through the septic tank which can be fixed out side the privy wall and a manhole should also be provided for removal of the sludge and where the tank is built underneath a privy ,the manhole should be made outside the privy wall and the inside dimensions of the septic tank should be 1.8 mts long and 0.75 wide and 1.8 mts in height with 150 to 230 mm air space.The effiuent is passed on to a soak pit or a filter chamber built adjoining the privy and then to the drainage system