The dirty water tank
I made the choice to put the dirty water tank in the lower part of the kitchen unit because this is the most practical solution if there is enough room: it is the shortest route from sink to tank, no problems regarding freezing and easy to clean. It is important not to forget the venting of the tank. I made a 5 mm hole in the lid and connected a 5mm tube with the outside through the bottom.
Position dirty water tank
Securing the dirty water tank
Throughput bottom floor connected with draining valve. Just as in the freshwater tank
venting is needed otherwise the air pressure will prevent the water to pass the hose to the dirty water tank. Therefore, I made a 5 mm hole in the lid and connected a 5 mm air hose leading outside.
Connection sink to water tank. Water hose and propane pipe in the background