Underground Stormwater Control for Sandy Ground

Where does roof water go when there isn't a convenient stormwater outlet at the surface? RELN Soakwells provide an underground pathway for rainwater from downpipes to disperse into suitable surrounding soil. They are particularly suited to sandy ground where infiltration can move captured stormwater away from buildings, paths & landscaped areas. Explore the broader RELN range when planning connected stormwater components around the property.

Unlike a sealed storage tank, a soakwell is designed to release water through its chamber into the surrounding ground. RELN uses a beehive-shaped reinforced-polymer design with drainage slots that promote water movement into the soil while helping the chamber withstand underground pressure. Where water first needs to be collected or directed through surface drainage, RELN | Drainage & Pits can form part of the wider stormwater layout.

Good drainage starts before the first shovel hits the ground. Roof catchment, downpipe location, soil infiltration, available space, pipe fall & the amount of runoff reaching each point should be considered together. A soakwell works best as one carefully planned part of the complete water path rather than an isolated chamber buried wherever space happens to be available.

What Are RELN | Soakwells?

RELN Soakwells are underground stormwater chambers designed to receive surface water from building downpipes & disperse it into suitable surrounding soil. Rather than holding rainwater indefinitely, the chamber creates temporary underground capacity while drainage slots allow water to infiltrate into the ground.

The RELN Soakwell system is built around three key components:

► Soakwell Base | 000865 – forms the reinforced-polymer chamber with openings for water dispersal
► Soakwell Lid | 000866 – closes the upper section of the chamber
► Soakwell Sock | 001245 – surrounds the chamber to help prevent sand entering through drainage openings

Its shape isn't simply cosmetic. RELN uses a beehive-style chamber profile to help withstand ground pressure after installation, while multiple drainage slots provide pathways for captured stormwater to move into the surrounding soil.

Why Choose RELN | Soakwells?

Some stormwater problems don't need another surface drain — they need somewhere for collected water to disperse underground. A correctly planned soakwell can receive downpipe runoff below ground while leaving lawns, pathways & surrounding outdoor areas usable above.

Key RELN Soakwell characteristics include:

► High-strength reinforced-polymer construction
► Lightweight modular components
► Beehive-shaped chamber for underground strength
► Drainage slots for water dispersal
► Knockout connection points
► Ability to connect multiple Soakwells
► Dedicated Soakwell Sock
► Suitability for sandy-soil applications
► Underground installation
► Downpipe stormwater distribution

Modularity becomes useful when one chamber isn't appropriate for the required runoff. RELN provides connection points that allow additional Soakwells to be incorporated where the site design calls for greater underground capacity or a broader infiltration area.

Common Applications

A downpipe emptying beside a house may look harmless during light rain, then become an entirely different problem during a summer storm. Soakwells are particularly useful where roof runoff needs an underground infiltration point rather than uncontrolled discharge across the surface.

► House downpipes – receive roof water & distribute it into suitable surrounding soil.
► Detached garages – provide an underground destination for roof runoff where the site arrangement suits infiltration.
► Sheds – manage rainfall collected from roof areas rather than allowing downpipes to discharge beside the structure.
► Residential pathways – support drainage planning where uncontrolled roof runoff contributes to wet surrounding ground.
► Garden areas – move captured rainwater below the surface where suitable soil conditions allow infiltration.
► Property drainage upgrades – replace uncontrolled downpipe discharge with a planned underground dispersal point.
► New residential builds – incorporate soakwells before landscaping & finished surfaces restrict excavation.
► Multiple-downpipe layouts – use separately planned or interconnected chambers where runoff volume requires more than one infiltration point.

Imagine two houses receiving the same rainfall: one sits on freely draining sandy ground while the other sits on slow-draining heavy soil. The same soakwell arrangement shouldn't automatically be assumed suitable for both. Soil behaviour is fundamental to whether infiltration drainage will perform effectively.

Where excavation forms part of a new drainage installation, Earthmoving & Excavation Equipment can support wider ground preparation once the drainage layout has been established.

Product Selection Guide

Check the Soil Before Choosing a Soakwell

Will the surrounding ground actually accept the water? That question matters more than how neatly the chamber fits into the available space.

RELN identifies its Soakwell for sandy-soil applications because the system relies on water dispersing from the chamber into the surrounding ground.

Consider:

► Soil type
► Infiltration behaviour
► Groundwater conditions
► Rainfall intensity
► Roof catchment area
► Existing drainage
► Local requirements
► Available installation area

Slow-draining ground can change the entire drainage approach. Don't assume an infiltration system is appropriate merely because standing water is visible at the surface.

Understand the Three-Part System

Base, lid & sock each solve a different part of the underground drainage problem.

Leaving out the sock changes how the chamber interacts with the surrounding soil. The dedicated RELN Soakwell Sock helps prevent sand from entering through the drainage openings while supporting the intended infiltration arrangement.

Understand the Beehive Shape

Why not simply use a straight-sided box underground? Ground pressure places loads around a buried chamber, so structural geometry matters.

RELN's beehive design helps create:

► A strong underground chamber
► Resistance to surrounding ground pressure
► Useful internal stormwater space
► Compatibility with reinforced-polymer construction

Buried drainage hardware still carries structural demands even when nobody can see it. Chamber strength needs to be considered alongside the conditions surrounding the installation.

Follow the Water From Roof to Soil

A soakwell can only manage water that reaches it properly. Trace the complete route before deciding where the chamber belongs.

A typical pathway may involve:

► Roof catchment
► Gutter
► Downpipe
► Connecting drainage pipe
► Soakwell inlet
► Underground chamber
► Drainage slots
► Surrounding permeable soil

Connections between these stages deserve attention before the trench is opened. Plumbing Fixtures & Accessories can support related pipework requirements, while the final drainage arrangement should suit the property, applicable requirements & intended stormwater route.

Size for Runoff, Not Convenience

The easiest hole to dig isn't necessarily the right drainage capacity. Runoff entering the system is influenced by the contributing roof area plus the rainfall falling across it.

Before settling on an arrangement, consider:

► Roof area feeding the downpipe
► Number of downpipes
► Local rainfall
► Soil infiltration
► Available underground volume
► Pipe configuration
► Number of connected Soakwells

Larger roof catchments can deliver substantial volumes of water in a short period. Capacity should reflect expected runoff plus site conditions rather than automatically assuming one chamber per downpipe.

Connect Multiple Soakwells Where Required?

What if one infiltration chamber isn't enough for the planned system? RELN Soakwells incorporate connection points that allow additional chambers to be incorporated into the drainage layout.

An interconnected arrangement can help:

► Increase underground capacity
► Distribute water across a larger infiltration area
► Accommodate greater roof runoff
► Adapt the layout to available ground space
► Create a more deliberate stormwater pathway

More chambers aren't a substitute for suitable soil. Additional capacity can help manage incoming runoff, but the surrounding ground still needs to accept the discharged water.

Position the Chamber With the Whole Property in Mind

The nearest patch of lawn to a downpipe isn't automatically the best location.

Consider the relationship between the proposed Soakwell &:

► Building foundations
► Property boundaries
► Driveways
► Paths
► Retaining walls
► Existing underground services
► Trees
► Future structures
► Other drainage infrastructure

Underground drainage should be planned around what already occupies the ground plus what may occupy it later. Check applicable requirements before determining final placement.

Plan Pipe Connections Before Digging

A chamber in the correct location can still become awkward if the inlet approaches at the wrong level.

Before excavation:

► Identify the feeding downpipe
► Establish required fall
► Identify the Soakwell inlet
► Check for underground services
► Confirm chamber orientation
► Plan any connection to additional Soakwells

Set-out is faster above ground than correction below it. Measuring & Leveling Tools can help establish pipe fall, ground levels & chamber position before excavation begins.

Understand the Soakwell Sock

Sand entering through drainage slots can occupy space intended for stormwater. The dedicated RELN Soakwell Sock creates a barrier around the chamber while allowing the system to perform its infiltration role.

The sock is designed to:

► Help prevent surrounding sand entering the chamber
► Support the intended underground installation
► Work with the dedicated RELN Soakwell components

Use the component designed for the chamber rather than improvising with unrelated material. Compatibility matters underground where correction becomes more difficult after backfilling.

Keep Surface Water Moving Towards the Right Place

A Soakwell handles downpipe water underground; it doesn't automatically solve every puddle across a property. Surface runoff from paved areas may require collection before water can enter an appropriate drainage route.

Driveways, courtyards, paths & landscaped areas can require:

► Surface channels
► Drainage pits
► Grates
► Correct surface falls
► Pipe connections
► Suitable discharge or infiltration points

Treat surface collection & underground dispersal as separate stages of the same water journey. This prevents the Soakwell from being expected to correct poor surface grading elsewhere.

Know When a Pump Solves a Different Problem?

A soakwell relies on infiltration; a pump mechanically moves water. Those are fundamentally different drainage solutions.

Where suitable ground can accept stormwater, a Soakwell may provide an infiltration point. Where water instead needs to be mechanically transferred to another level or approved destination, RELN | Pumps addresses a different type of water-movement problem.

Don't add pumping equipment simply because a site has drainage trouble. First establish whether the issue is collection, infiltration, elevation, discharge capacity or a combination of these conditions.

Protect Finished Landscaping From Rework

Drainage is far cheaper to change before paving, turf & garden beds are finished.

For new builds or landscaping projects, determine:

► Soakwell locations
► Downpipe routes
► Connection points
► Excavation access
► Finished ground levels
► Future inspection locations

before completing expensive surfaces.

A simple drainage sketch can become extremely valuable years later. Photograph chamber locations plus pipe routes before backfilling & record measurements from fixed property landmarks.

Prepare for Wet-Weather Installation Conditions

The day a drainage problem becomes obvious is often the worst day to start digging. Saturated ground can make excavation, access & backfilling more difficult.

Plan the work around:

► Ground stability
► Weather conditions
► Excavation access
► Spoil placement
► Safe working areas
► Existing runoff
► Required protective equipment

Work Safety Protections can support wider site preparation where drainage work introduces excavation, wet-ground or handling hazards.

Expert Tips

► Test the ground assumption first. Soakwells depend on surrounding soil accepting water, making soil suitability a central consideration.
► Measure the contributing roof area. Catchment size influences how much stormwater reaches each downpipe.
► Map every downpipe. One overlooked roof section can change the expected runoff considerably.
► Don't confuse storage with infiltration. A Soakwell temporarily receives water so it can disperse into the surrounding ground.
► Use the dedicated sock. It helps keep surrounding sand from migrating into the chamber.
► Plan multiple chambers before excavation. RELN's connection points make an expanded arrangement possible where required.
► Maintain appropriate pipe fall. Poor levels between the downpipe & chamber can undermine an otherwise sound layout.
► Photograph the open excavation. Pipe routes become much harder to identify after landscaping is complete.
► Record distances from fixed landmarks. Fence corners, walls or other permanent reference points make future location easier.
► Check underground services before digging. Drainage improvements shouldn't create electrical, plumbing or communications problems.
► Don't rely on chamber capacity alone. Soil infiltration remains part of the system's ability to clear incoming water.
► Finish drainage before premium landscaping. Correcting buried pipework after paving or planting adds unnecessary cost.
► Keep different water problems separate. Roof runoff, surface pooling & groundwater can require different drainage approaches.

► Reassess after major property changes. Extensions, patios, sheds or additional roof area can increase runoff entering the drainage system.