Why should oil and fats be not released in the drain ? Explain

Dear Student, Oils and fats harden and block the sewage pipes.In an open drain also, fats block porosity of soil which affects itswater filtering efficiency. That is why oils and fats should not bereleased in the drain. In other words, Fats and oils are very sticky materials. If they are disposed of in drains, they stick the walls of the drain and other pipelines of sewage system. This can block the pipes resulting in a problem in sewage system. Regards