They are used where the installation of wastewater is collected in the ceiling of a lower floor and where it is desired to strictly prevent water infiltration to the lower floor. As a result of the deterioration of the coating on the floor or the joints around the floor drain, the leaking water percolates up to the insulation floor and can flow to the lower floors from a point where the insulation is weak.

Floor drains with isolated-bottom outlet collect the water leaking to the isolation floor and convey it to the wastewater installation. No water leaks downstairs. It is used in areas such as hotels, restaurants, bars, hospitals, laundries, dishwashers.