Sustainable infiltration for clay

Effective onsite clay soil infiltration using Hydrorock - filled boreholes

Unitary aquifer created

Bridging contact between Hydrorock and the permeable layer creates a huge unitary natural aquifer

Dispersed system

Module configurations can be dispersed in many shapes and sizes, to suit site requirements and optimise land use

Additional capacity

Further blocks can be easily installed above the bore holes to add buffering capacity.

No micro particle release
Works in dense clay soils
Lifelong operation

Hydrorock natural aquifer blocks provide sustainable drainage solutions for onsite clay soil infiltration. Hydrorock filled bore holes provide natural conduits for the rapid percolation of surface water to the permeable layer of soil beneath.

  • Sustainable infiltration for clay soils
  • Hydrorock surface buffering block arrays combine with Hydrorock filled bore holes to create unitary aquifer deep below the surface
  • Smaller modules can be dispersed across site to optimise land use
  • Highly configurable system
  • Uniquely high absorption to volume ratio (94%)
  • 100% natural product
  • Recyclable
  • Non-plastic solution, no micro particle release
  • Full integratable with other Hydrorock infiltration or filter drain systems
  • Lifelong, maintenance-free  effective operation

Design detailing

Working with nature is key to unlocking SuDS on clay soil

The ClaySolve system comprises of boreholes drilled through the clay, filled with Hydrorock natural aquifer blocks to provide natural conduits for surface water to rapidly percolate down, and infiltrate into the permeable layer beneath.

The bridging contact between Hydrorock blocks and the permeable layer has the effect of creating a huge unitary natural aquifer, reaching from the surface to deep underground. A range of Hydrorock BD or HD blocks can be installed in a trench directly above the boreholes to provide the system with any required additional buffering capacity.

Optimises site land and maximises construction

Hydrorock blocks are solid, pre-wrapped with geotextile and can be installed immediately adjacent to buildings, eliminating the large construction exclusion zones required by big centralised, crated water sumps.

ClaySolve’s high efficiency and Hydrorock’s modularity, enables small sized infiltration systems to be dispersed across the site. This allows developers to optimise land use and maximise onsite construction.

  • Configuration of a ClaySolve System depends on key project site variables, including water volume, soil type, permeability, thickness of clay soil to permeable layer, site area and layout.
  • The test drilling is recommended to ascertain depth, thickness and of the permeable layer.
  • Larger systems may require air venting capability to enable required rapid water inflow into the system.
  • Systems can be designed with a looped water inflow system, for more rapid inflow and cleansing if the inlet filters are compromised.
  • All systems should be fitted with a filtered inlet. There are three sizes depending on volumes.


  • Minimum trench excavation requirement 1 m W x 1.3 m D x 5 m L.
  • A 325 mm diameter borehole should be drilled in the middle of the trench through the clay layer and at least one 1m into the permeable layer.
  • The borehole should be filled with Hydrorock IR40 blocks (cm 100 L x 20 W x 20 H) stacked tightly and vertically end to end.
  • Total number of boreholes required will depend on system capacity and the infiltration rate of permeable substrate.
  • The bottom Hydrorock block should touch the bottom of the borehole and the top block should protrude 50 mm above the top of the hole at the bottom of the trench.
  • The bottom of the trench should be filled with a levelled sand layer 100 mm thick.
  • Hydrorock BD440 blocks (cm 120 L x 100 H x 40 W) should be placed into the trench on the sand stacked tightly together in pairs and abutted end to end.
  • Other blocks from the Hydrorock range with varying sizes and densities specified according to system capacity requirements and above surface weight loading.




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