What Causes Sinkholes in Gardens?

Garden sinkholes are almost always caused by a collapsed or broken drain pipe underground. When a pipe fails, soil surrounding it gradually washes into the pipe through the breaks, creating an underground void. Eventually, the ground above can no longer support its own weight and collapses, forming a visible sinkhole.

What to Look For

• Collapsed drain pipes allowing soil to wash into the void
• Water erosion from leaking pipes washing away surrounding soil
• Old brick soakaways or cesspits collapsing after decades
• Natural ground shrinkage in clay soils during dry periods
• Tree root decay leaving voids when old roots decompose
• Previous excavation work that was poorly backfilled

How We Diagnose the Problem

We use CCTV drain surveys to inspect pipes in the sinkhole area, drain tracing to map pipe routes, and ground investigation to assess the extent of soil washout. This comprehensive approach identifies the cause and determines the full extent of the problem.

How We Fix It

We excavate the collapsed pipe, replace the damaged section with new pipework on properly compacted bedding, and backfill the void with graded aggregate. Garden surface reinstatement is included. For old soakaway collapses, we install modern alternatives.