Sealing is indispensable for environmental and groundwater protection and contributes substantially to the fitness for use and service life of buildings. Especially in water protection areas the adjacent soil must be protected from possible seepage of contaminated surface water. The water is collected and fed to the appropriate recipient by the shortest path. In order to prevent seepage, the sub-grade is covered with a layer that is impermeable to water over the desired area.Mineral seals, plastic membranes and geosynthetic clay sealing liner can be used for this purpose. During installation, attention should be given to the different special requirements.