Septic concrete tanks have been specially developed for domestic wastewater from toilets, in other words; faecal waste water. The septic tanks are standard equipped with inlet and outlet, both with rubber sealing. The lower part of the septic concrete tank is manufactured in one piece, so it is guaranteed to be watertight. The septic tanks of concrete are provided with four lifting loops in the cockpit, not in the upper deck. The great advantage of this is that the deck does not get damaged as quickly as the deck plates through which the lifting loops penetrate. In the longitudinal direction there is a dividing wall that divides the septic tank into two compartments. The septic tanks are suitable for traffic class A and can be supplied on request with a heavier deck for larger traffic classes.