Every type of waste water retention system on board must meet special requirements. Tanks and hoses must be securely fastened. This may require some technical effort, especially for retrofits with complicated installation conditions. The maximum volume can be achieved by using customised tanks for given space conditions. Alternatives are flexible faecal tanks, but these must be constructed with a stable and abrasion-resistant protective cover to prevent chafing. CE-approved waste water tanks are mainly manufactured with thick walls of high-quality, absolutely odour-proof plastic. Just like a water tank for fresh water, a waste water tank must also be pressure-tested and, if it has a larger capacity, equipped with baffles.
Neither container, hose system nor connections should cause unpleasant odours. Leakages caused by vibrations and ship motions are prevented by double hose clamps and careful fastening. Larger, screw-on tank caps are used as inspection openings, through which the waste-holding tank can also be rinsed and cleaned. The tank connection cap with flange for the connections of supply and discharge pipes must be screwed and sealed with particular care. Among other things, ventilation lines, filling line and the line for emptying are connected to the mounting flange. For this purpose, the tanks must also have openings for tank sensors for level indication.
A faecal tank indicator or level indicator is part of the instrumentation of a waste water tank system. The level can be measured by various sensors on and in the tank. Either with capacitive level probe, mechanical lever sensors or ultrasonic sensors. Universal tank sensors can be used both for holding tanks as well as for water level indication of drinking water tanks and fuel indication of diesel tanks. The sensors can be programmed to the tank size. The current fill level can be read off via LED displays or classic pointer instruments.