Reservoir Drainage & Dam Structures

With a long history of manufacturing and supply of high performance drainage geocomposites for the Water Industry, Geotexan’s products offer an efficient and cost effective alternative to stone drainage layers. The reduction of stone drainage offers significant carbon footprint reductions, reduced labour and installation times, and ultimately, reduced overall costs.

An extensive range of options are available for incorporation on, around, and under buried concrete structures; including covered reservoir roof and wall drainage, potable water storage, ground water drainage and flotation protection to water storage and treatment tanks.

Typical applications

  • Relief of external water pressure from buried structures
  • Drainage behind retaining walls
  • Covered reservoir roofs and walls
  • Relief of uplift pressure beneath tanks, slabs and culverts
  • Structural drainage


  • Horizontal or vertical drainage applications (walls)
  • Reduced thickness of drainage layers when compared to traditional aggregate drainage stone
  • Reduced dead loads on structure means thinner slabs are possible
  • High, factory controlled constant flow capacity
  • Wide rolls of Deckdrain are suited for rapid installation, reducing construction time
  • Enhances the performance of structural waterproofing by providing an additional barrier that prevents the majority of the water reaching the liner.
  • High CBR puncture resistance of Deckdrain® provides protection.
  • Allows use of lower specification backfill
  • Reduced traffic volumes to site when compared with stone, meaning reduced carbon footprint and fewer vehicle movements

Dam walls & slopes

Geocomposite solutions can be specified for dam slopes where overspill capacities are to be increased to cope with storm events. In such cases Reservoir Panel engineers require a drainage system to increase the stability of the regraded spillway embankments and to provide drainage to the depth of fill to be placed.

In summary Drenflex options can provide efficient filtration without clogging and to prevent piping, alongside adequate flow capacity to channel rainfall and the anticipated seepage during the product’s design life.

Basin & Open-air reservoir construction

Reservoir linings are subject to large pressures from the head of water acting on it when the basins are full. In order to achieve the required design life of the reservoir and geomembrane, it is essential to protect the integrity of the lining system. A high performance geotextile layer is used to protect the geomembrane against any damage or puncture and provide separation between the liner and the underlying formation.

Slope Erosion Control

Permanent and degradable erosion control mats are also available for dam slope construction in order to protect fill from slipping / slump before grass is able to establish.

Erosamats Type 1 biodegradable coir offers temporary protection and by absorbing the impact energy of rain bombardment and reducing surface water run-off velocities they give the newly establishing vegetation the best possible chance of survival.
Erosamat Type 3 works by providing an interlock for vegetation root systems, better enabling the vegetation to resist high shear/stress situations. It is non-biodegradable and has a design life of 120 years.

Typical Client Profile

  • Waterproofing Contractors
  • Drainage Contractors
  • Water, Wastewater, and Utilities Companies
  • Covered Reservoir Engineers
  • Structural Engineers

Additional information

Contact Geotexan for further information

Fill out our quick contact form with your product, application, technical or sales enquiry and one of our team will be in touch soon.