Soakaway Installation in Wolverhampton

Signs a Soakaway Is Failing

The most obvious sign is water that collects after moderate rainfall and drains away slowly or not at all. If the lawn immediately above or beside the soakaway becomes consistently waterlogged after rain — even in summer — the system is silted up, collapsed, or no longer able to accept water at the rate the downpipes are delivering it. Backed-up gutters that overflow despite being clear of leaves, persistent wet patches on a drive or path, or water running against the base of a wall rather than away from it are all worth investigating.

Older soakaways — particularly those built from rubble, brick, or perforated concrete rings — tend to silt progressively as fine soil particles wash in with the surface water and clog the drainage matrix. Eventually the voids fill and the system stops accepting water. Polypropylene crate soakaways, which are the current standard, have better long-term performance but are not immune to silt ingress if the inlet filter or geotextile wrapping has degraded.

Assessment First

We assess ground conditions before recommending any installation. The standard test is a percolation test — a hole is excavated to the proposed soakaway depth, filled with water, and the rate at which it drains is measured. This gives us a reliable indication of whether the ground will accept water at the rate needed to keep pace with the roof drainage area it is serving. Wolverhampton has variable ground conditions: sandier, more permeable soils are found in some parts of the city, while the heavier clay bands that run through parts of the Black Country drain much more slowly.

If the percolation test indicates that a soakaway is not viable in the proposed location, we tell you honestly rather than installing a system that will fail within a few years. In that situation we can advise on alternatives — connecting to a surface water sewer where one is available and adoption by Severn Trent is agreed, or a drainage channel that routes water to a suitable discharge point.

Installation Process

Where the ground is suitable, we excavate to the required depth — typically a minimum of 1 metre below the inlet pipe, and at least 5 metres from any building foundation. The excavation is lined with geotextile membrane, which allows water to pass through while preventing soil migration into the crate matrix. The polypropylene crate units are assembled in the hole to the required volume, the geotextile is wrapped over the top, and the inlet pipe is connected. The hole is then backfilled and the surface reinstated.

Volume is calculated from the roof area draining to the soakaway and the local design rainfall intensity. We size the system to handle a significant rain event without overflowing — a correctly sized soakaway should not back up in normal rainfall conditions, only in extreme events that exceed its design capacity. We install to the requirements of BRE Digest 365 and current building regulations.

Replacement

If an existing soakaway has failed and is beyond cleaning — a silted rubble soakaway, a collapsed ring system, or a crate that has degraded — we excavate and replace it. In most cases this means taking out the old system, assessing whether the same location still has adequate percolation, and installing a new crate system in the same or a nearby position. Sometimes a failed soakaway can be relocated to a part of the garden with better ground conditions — the percolation test helps us identify the best position.

Where an old soakaway simply needs clearing rather than replacing — and where the structure is still sound — we can jet it out through the inlet, flushing accumulated silt through a temporary hose. This is not always possible depending on the soakaway type and how silted it has become, but where it is an option it is considerably cheaper than replacement. We assess this on site and advise before any work starts.

See also: Drainage Repairs, Outside Drain Blocked, Domestic Drainage