I have an independent house in Thiruvallur, Tamil Nadu. I had constructed a septic tank in 2005 with the dimension 8ft X 5ft X 8ft, for only the toilet waste (the kitchen, bathing, and cloth washing waste is channelled to a small drain outside the house). We are a family of five and use only one Indian style toilet in the house. Over the last two years my septic tank is getting filled up every 4 months which used to get filled in 7-8 months previously (from 2005-2012).  Kindly advice what to do in such case?