The wall in a septic tank is commonly known as the "baffle wall." This essential component serves to separate solid waste from liquid effluent. The baffle wall directs incoming wastewater downward, allowing solids to settle at the bottom while allowing clarified effluent to flow towards the tank's outlet. Proper functioning of the baffle wall is critical for the efficient operation of the septic tank system, ensuring that solids are retained within the tank and preventing them from clogging the drainage field.