What should I ask about surface-water drainage?

Follow the likely water route

Look at the relationship between roofs, terraces, driveways, planted areas and neighbouring ground. Ask where gutters and channel drains discharge, whether water collects near entrances and what happens when leaves or soil obstruct outlets. Never enter drains or lift heavy covers yourself.

Request the seller’s account of heavy-rain events, cleaning routines and past works. Photographs or maintenance records may help, but a dry-day inspection cannot demonstrate how the system performs in demanding conditions.

Check design and responsibility

Ask an independent engineer to assess the visible arrangement and identify any need for further investigation. A proposal to divert water elsewhere should not be accepted without checking technical suitability and the rights or approvals involved.

If water passes through shared land, a neighbouring plot or a common system, have your lawyer establish the relevant arrangements. Clarify access for cleaning, responsibility for repairs and how disputes or blockages are reported. Treat drainage as part of the property assessment, not merely a gardening matter, especially where lower rooms or retaining structures could be affected.