The fact of bringing oxygen by sequences allows to limit the development of bad smells.
The disadvantage of this technique is that the sequences, which last from 4 to 8 hours depending on the model, still leave time for the bad odors to partially develop.
Moreover, these odors are expelled from the device at the end of each sequence and are found in the immediate environment of the installation.

Their more recent design than sand filters allows them to be much more compact, and therefore to consume less space in the grounds.
The disadvantage concerning the production of bad smells remains the same as for the classic sand filters.

The technology known as "fixed cultures" allows for the injection of a large quantity of air into the system, but only in the compartment located after the all-water tank.
The all-water tank thus keeps all its potential for producing bad odors. It should be noted, however, that the production of malodorous gases is still reduced by the recirculation of the treated sludge which is reinjected via the recirculation in the all-water tank section.
This treated sludge, rich in oxygen, allows a slight decrease in the production of gases.

In spite of the efforts made to reduce the risks of bad odors, the classic all-water tank with sand filter system cannot function without producing them. This is the result of a choice of design of non-collective sanitation systems from the 1950s.
The only solution for these systems is to release the unpleasant gases by diluting them in the atmosphere with the help of secondary ventilation installed on the roof of the house.