Garden Flooding After Heavy Rain

Watch the garden in a downpour and note where water enters, where it travels and where it stops. Check that downpipes and gullies actually connect, and that they are not discharging onto a lawn.

Where water comes from a neighbouring property, it becomes a conversation as well as an engineering problem.

Permeable surfacing, gravel margins, rain gardens and planted swales all reduce run-off at source. On clay, storage matters as much as infiltration because the ground accepts water slowly.

A soakaway needs to be sized for the catchment and sited away from foundations.

Ground levels adjacent to the building should fall away and stay well below the damp proof course. A threshold channel drain with a proper outfall is the standard defence where levels are tight.

Raising patios over the years without checking that level is a surprisingly common cause of water at the back door.