Soakaways in London

Soakaways in London: what the price includes

• 01
  Percolation test first, always

  BRE Digest 365 sets the method: dig the trial pit, fill it three times, time the drop. It tells you whether a soakaway will work here at all and how big it has to be. Anyone quoting without one is guessing, and on clay they are usually guessing wrong.

• 02
  Sized to the roof, not to the hole

  The volume is calculated from the area draining into it and the measured infiltration rate. Undersized soakaways do not fail immediately, they fail in the first serious storm, which is the worst possible time to discover it.

• 03
  Crates or rubble, and why it matters

  Modular crates give roughly 95% void against about 30% for rubble, so they do the same job in a third of the excavation. Wrapped in geotextile, they also stay clear far longer. On a small London garden that difference decides whether the job is possible.

• 04
  Distance from the building

  Five metres minimum from any structure under Approved Document H, and further on shrinkable clay. Too close and you are irrigating your own foundations, which is the cause behind a good share of the "mystery damp" we get asked about.

• 05
  Unblocking an existing one

  Most failed soakaways are not broken, they are silted. Jetting the inlet, excavating the inspection point and flushing the media brings a lot of them back for a fraction of a replacement, and we will always test that before quoting a new one.

Local conditions we work around

Soakaways are harder to get right in much of London than people expect, because London clay drains slowly and the water table in low-lying areas sits high. A percolation test is what decides whether a soakaway will work at all on your ground, and skipping it is why so many fail within a couple of winters. Where the ground will not take it, the honest alternatives are attenuation or a permitted surface-water connection, and we will say which your site actually needs.

Where we work in London

Same price and the same guarantee in every area below. Each has its own page with the streets we cover.

Soakaways in London, your questions