Drainage capacity in Merton: the usual causes
Merton is mostly suburban, with interwar semi-detached houses in Morden and Mitcham, Victorian terraces closer to Colliers Wood and newer developments along the main routes. Most properties have their own garden drainage.
Building over or near an existing drain brings its own requirements, and getting that wrong is expensive to correct once the structure is up.
The River Wandle runs through the borough and the ground alongside it holds water, so gardens drain slowly and soakaways fill during prolonged rain. Where a driveway has been paved without drainage, that water goes straight into the foul system.
How we deal with drainage capacity in Merton
The sequence is survey, design, fixed quote, installation, then a camera check before we backfill.
- Survey the existing drainage and establish where a new run can connect
- Design the layout with the falls, diameters and access points it needs
- Confirm a fixed price against that design before any work starts
- Excavate, lay and bed the pipework, and build the chambers
- Camera the finished run and test it before backfilling and reinstating
Off-street parking and side access make these jobs relatively straightforward. Where a chamber has been covered by a driveway, we trace the run with a camera and locator instead of lifting slabs blind.
Signs it needs attention now
- An extension or loft conversion adding bathrooms to the property
- A garden that floods or stays waterlogged after rain
- A paved or decked area with nowhere for surface water to go
- Drainage that was never adapted after a previous alteration
- A property being converted into flats with new kitchens and bathrooms
What we see most often in Merton
- Waterlogged ground alongside the Wandle holding surface water
- Soakaways filling and failing to discharge during prolonged rain
- Inspection chambers buried under later driveway work
Merton work is mostly suburban and mostly for owner-occupiers, with off-street parking and side access making visits efficient. We also attend a steady number of garden drainage jobs where rainwater has nowhere to go.
Equipment and what happens afterwards
Installation work uses pipe, fittings, chambers and bedding material specified for the job rather than whatever is on the van. Falls are set with a level rather than by eye, and chambers are positioned where they will still be reachable in ten years, not where they are easiest to build today.
Before anything is backfilled we camera the new run and test it, so any issue is found while the trench is still open. You get that footage, a description of what was installed and where the access points are. Reinstatement is agreed in advance and included in the fixed price rather than treated as an extra.
What drainage installation cost in Merton
Installation work typically runs from £600 to £2,500 depending on the scope, and the fixed price is confirmed after a site visit. There is no call-out charge in Merton, at any hour, and the price you are given on the call is the price you pay.
Areas we cover around Merton
Our Merton work covers SW19, SW20, CR4 and SM4 and the rest of Merton. Engineers are usually 60 to 90 minutes away, and because we also cover Wimbledon, Croydon, Balham and Wandsworth, a job that crosses a boundary does not need a second contractor.