Highway Filter Drains

Excellent polution filtration

More efficient than gravel counterparts and 30 year filter guarantee

Excellent water storage

Double the capacity compared with gravel systems

Streamlined installation

No temporary shoring works, less excavation, fewer lorry trips required

Fully integratable

Highly configurable to suit site conditions and fully integratable with other Hydrorock systems

Excellent pollution filtration
Touching blocks create unitary aquifer
No temporary shoring work required

Designed to remove run-off quickly and efficiently from highways or road surfaces, Hydrorock natural aquifer block highway filter drains have far higher storage and infiltration characteristics than gravel options and have excellent pollution filtration properties.

They are easier, safer and faster to install and are easily configurable to suit site conditions and in-ground problems.

  • More efficient than gravel counterparts
  • Excellent filtration of pollution
  • 30 year filter guarantee
  • Double the water storage capacity compared with gravel
  • No temporary shoring works required
  • 15% less soil excavation  (by volume and weight)
  • 60% less infill weight (far fewer vehicle loads required with Hydrorock)
  • 33% bigger infiltration surface area (much more efficient than gravel system)
  • 30 year filter life (double gravel 15 year filter life)
  • Free recycling by Rockwool (gravel needs expensive cleaning)   
  • Full integratable with other Hydrorock infiltration or filter drain systems
  • Excellent load bearing up to 40 tonnes and life time system integrity
  • Uniquely high absorption to volume ratio (94%)
  • 100% natural product
  • Recyclable

Design detailing

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Installation is very simple and quick with minimal disruption.
Blocks are pre-wrapped with filter membrane, so the excavation needs to be only as large as the system (no access is required to fit the membrane).

  • No specialist installation engineering or equipment is needed, with simple snap-together fittings which require no special skills or tools.
  • Hydrorock natural aquifer blocks can be used in single or multiple layers, on a 100 mm layer of sand. This increases the surface area of the bottom of the system.
  • The Hydrorock blocks are normally installed in a module three blocks wide. This allows for the system to self-vent, and if by human error the filters are compromised, the whole system can be flushed.
  • Hydrorock BD blocks have integrated perforated pipes allowing rapid inflow and storage water in each block underground.
  • Additional capacity can be rapidly and easily achieved by the addition of further Hydrorock BD blocks or Hydrorock B blocks (pre-wrapped but without integrated pipes)
  • The system can be placed around existing infrastructure, such as pipes and cables unlike crated sumps. This flexibility allows for optimisation of the site.
  • Placing the system on a 100mm layer of sand will permit infiltration from the module into the surrounding soil and facilitate the discharge of water from the Hydrorock blocks.




Click here to use our calculator and quickly calculate the number and volume of Hydrorock natural aquifer blocks needed for your application.


Hydrorock natural aquifer blocks are available to provide 100% sustainable, 100% recyclable water management solutions.

D Block
D Block
BD Block
BD Block
DHD Block
DHD Block
BDHD Block
BDHD Block
BD Block
IR Block
LG Block
LG and SL Blocks
IP Range
IP Range
Filter units
Filter units
Hydrorock fixings and connectors
Hydrorock fixings and connectors