How Does A Soakaway Work
The Welfare Hire Co. is a UK-based company that provides temporary welfare facilities for construction sites and outdoor projects. Their offering typically includes portable toilets, mobile welfare units, and site accommodation designed to support workers on-site. The company focuses on compliance with health and safety regulations, ensuring sites have proper sanitation and welfare provisions. They also publish practical guides and resources related to construction, groundwork, and equipment usage. Overall, their service is aimed at making worksites safer, more efficient, and fully equipped for day-to-day operations. Welfare Hire Direct is a UK-based company that specialises in providing eco-friendly welfare units for construction and site-based projects. Their main offering includes solar-powered units equipped with toilets, canteen areas, drying rooms, and workspace facilities. The company focuses on sustainability, using solar energy with biofuel backup to reduce emissions and fuel costs. They deliver and service units nationwide, ensuring they are ready to use and compliant with site requirements. Overall, their services are designed to support on-site teams with reliable, self-contained welfare facilities while minimising environmental impact. “
How does a soakaway work?
A soakaway is a simple but crucial piece of drainage infrastructure used across the UK to manage surface water and treated water from buildings and civil engineering works. In practical terms, it provides a controlled place for rainwater (or certain run-off) to soak into the ground, helping to reduce flooding risks, avoid overloading drainage systems, and protect nearby properties.
Soakaways are commonly used where connecting to mains drainage is difficult, where site conditions require infiltration, or where regulations and planning requirements favour soakaway-based drainage. For construction sites—such as those supported by The Welfare Hire Co. with portable welfare units and site facilities—understanding soakaways helps you plan drainage properly around temporary structures, hardstanding areas, and welfare amenities.
The basic principle: controlled infiltration
The underlying idea is straightforward: water is directed into a soakaway structure and then allowed to percolate into the surrounding soil. The soakaway acts as a temporary storage reservoir, holding water long enough for it to infiltrate safely into the ground.
Soakaways are designed to balance two needs:
1) Storage — They capture water and hold it, even when rainfall is heavy.
2) Infiltration — They allow the water to slowly filter downward through the soil.
Because the rate at which water soaks away depends on soil type and groundwater conditions, a soakaway is never a “one size fits all” solution. Good design and site investigation are essential.
Most soakaways used in building and groundwork settings include void space (for example, aggregate or crates) and a surrounding drainage system that directs water into that void space.
Common soakaway components include:
• Inlet pipe or connection: Receives water from a gutter drain, downpipe, yard drainage, or pipework serving a drainage run.
• Inspection and maintenance access: Often a manhole or chamber, allowing inspection and clearing of debris.
• Permeable structure: Typically washed stone with high void content, or proprietary storage crates designed to hold water while providing empty space for infiltration.
• Geotextile (in many designs): Helps prevent fine soil particles clogging the stone voids, improving long-term performance.
• Outlet/percolation zone: The surrounding soil is the final “drain.” Water moves downwards through the ground profile.
The specific materials and arrangement depend on the site’s soil and hydrogeological conditions, the size of the drainage catchment, and relevant regulatory requirements.
Water enters the soakaway via an inlet, usually from a pipe network that collects surface water. The flow may come from:
• Rainwater harvesting systems or downpipes
• Drainage from paved areas or roofs
• Land drainage connected to works and site infrastructure
Once water enters the soakaway, it does not instantly disappear. Instead, it collects within the void space. This “storage” function is vital because rainfall can be intense and short-lived. The soakaway absorbs the peak flow and then releases it slowly into the ground.
Most soakaways perform through three stages:
1) Immediate storage
Water flows in and fills the voids within the soakaway structure. Depending on design, this may be partly filled under normal conditions and fully utilised during heavy rain.
2) Infiltration into soil
As the soakaway fills, the water begins to percolate outwards and downwards through the surrounding soil. The infiltration rate is controlled by soil properties such as permeability and texture.
3) Filtering and gradual release
As water moves through soil, it is naturally filtered to some extent. The soil acts as a buffer and helps reduce solids that could otherwise clog the structure.
Over time, however, soakaways can become less effective if silt, organic debris, or fine particles enter the inlet. That is why filtration measures and maintenance plans matter.
In the UK, whether water can safely soak away depends heavily on ground conditions. If infiltration is poor, the soakaway may overflow or become ineffective, potentially increasing flood risk.
Site investigation typically considers:
• Soil type and permeability (e.g., clay vs sand and gravel)
• Groundwater levels (high water tables can prevent infiltration)
• Depth to impermeable layers (e.g., rock or dense strata)
• Whether the soakaway could affect nearby foundations or basements
During construction or groundwork planning, this investigation is usually part of a wider drainage design process, often requiring calculations and adherence to standards and local authority requirements.
A well-designed soakaway takes account of how much water it needs to handle and how fast the ground can accept it. Design variables commonly include:
• The size (volume) of the storage area
• The surface area footprint (distribution of void space)
• Depth and separation distances (for safe infiltration and to avoid groundwater contamination)
• Inlet arrangement and silt control measures
• The likely catchment area and rainfall intensity
For small domestic installations, soakaway design often follows accepted guidance and simplified methods. For larger projects, or where constraints are complex, detailed calculations and specialist input may be necessary.
Soakaways need periodic checks to ensure they remain functional. Key maintenance tasks can include:
• Inspecting the inlet and access points for debris build-up
• Clearing blockage risks (especially in gully connections and inspection chambers)
• Checking for signs of localised ponding, slow discharge, or unexpected overflow
Even well-filtered drainage can carry fine solids over time. Where maintenance is neglected, the soakaway can silt up and lose void space, reducing infiltration capacity.
Practical warning signs that a soakaway may be underperforming include:
• Water pooling on or near the drainage area long after rainfall
• Repeated backing-up of surface water toward adjacent areas
• Unpleasant odours if trapped drainage becomes stagnant (particularly where organic debris is involved)
• Evidence of erosion or sediment migration around the inlet connection
In construction site environments, these issues can be amplified by dust, mud, and general site traffic. That’s why temporary drainage arrangements and welfare facility positioning should be planned carefully, including how water is routed away from toilets, welfare units, and hardstanding.
Soakaways on construction and welfare sites
For worksites, soakaways may be used to manage rainwater and surface run-off from areas such as:
• External welfare unit zones
• Site access routes and hardstanding areas (where permitted)
• Temporary drainage networks serving non-foul water streams
It’s important to note that soakaways are intended for appropriate water streams (typically clean surface water or suitably treated drainage), not for foul sewage. Welfare facilities must be connected to proper sanitation arrangements and comply with health and safety requirements for the safe handling of human waste.
In summary
Soakaways work by collecting water in a storage structure and allowing it to infiltrate gradually into the surrounding ground. Their effectiveness depends on soil conditions, design size, depth, and infiltration capacity, as well as proper filtration and ongoing maintenance. Done correctly, a soakaway provides a reliable, low-maintenance drainage method that can help manage rainfall and reduce the risk of surface flooding.
If you’re planning temporary welfare facilities or drainage around an outdoor project, it’s worth speaking to a competent drainage designer or contractor and ensuring your temporary arrangements are appropriate, inspected, and compliant for the specific site conditions.
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