Tree pits

Excellent pollution filtration

Hydrorock natural aquifer blocks effectively filter run off from roads or paved areas

Stand-alone solution

Hydrorock tree pits buffer store and irrigate in a sustainable way, independently of the sewer system where required

Resistant to root growth

Pre-wrapped geo membrane resists roots growth and save on installation time

Enhances tree growth

Hydrorock stores, then releases water to trees when needed, optimising green spaces

Buffers street level water
Infiltrates and irrigates
Non-plastic solution

Hydrorock tree pits control and attenuate surface water run off, minimising flood risk in urban environments. Hydrorock solutions can deal with high rainfall events without the need to connect to a sewage or drainage system, instead storing the water locally and releasing as trees require.

  • Hydrorock natural aquifer blocks buffer, store and irrigate in a totally sustainable way
  • Hydrorock effectively filters road run off
  • Hydrorock not compromised by root growth
  • Water storage properties allow release of water to irrigate trees when needed
  • High density block options allow for urban load bearing options
  • Fast simple installation
  • Uniquely high absorption to volume ratio (94%)
  • 100% natural product
  • Recyclable
  • Non-plastic solution, no micro particle release
  • Requires minimal excavation
  • Full integratible with other Hydrorock infiltration or filter drain systems

Design detailing

Hydrorock natural aquifer block tree pits are designed to suit site conditions, numbers, species and spacings of trees, local rainfall event requirements and many other criteria.

A typical configuration for stand-alone tree pits in an urban but non-vehicular load bearing location is shown below.

3- module array

4-module array

In the each sub array, three or four BD 340 blocks were used at a depth of 1300mm, arranged to the side of the tree under the existing parking spaces, with a further block directly in front of the tree. The blocks were connected to ensure fast filling of the sub array.

Not only did the system cause minimal disruption during installation but it is also maintenance-free post installation.


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 push-together blocks and 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
  • Multiple block configurations are possible to suit site requirements
  • Extra capacity is provided by adding further blocks, which, on contact with others, become unitary aquifers
  • 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.

Projects can be undertaken with minimal disruption with sections of the road or paved areas being dealt with sequentially to maintain area usage and further minimise disruption.

The trees are generally located  at intervals dictated by parking spaces or other existing infrastructure and the system is installed around these trees to avoid root disturbance. The installation process is relatively simple and often existing paving materials can be re-used post installation.

Where areas are not subject to heavy vehicular traffic, standard-density blocks can be used, but high density blocks are also available for solutions in trafficked areas.




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