Closed underground tank

The closed tank is not a treatment but only the collection of the toilet water. Closed tanks are not recommended for mixed household wastewater.

Today, closed tanks are normally prohibited unless you have very low-flush toilets or a vacuum system.
All to reduce transportation by sludge truck and the load on the municipality’s treatment plant.

Level alarms are always a requirement, there are several different models to choose from, you can find them at this link.

It is often profitable to increase the size of the tank to save on emptying costs.
In almost all municipalities, the maximum distance between the sludge truck and the tank is 10 meters, which means that you sometimes need to buy an extension hose.

The groundwater level must never exceed the bottom of the lowest tank penetration (penetrations are only sealed from the inside).

There must be ventilation from the closed tank and it is very common to use an odor trap to remove odors.