Garden Drainage Solutions for Waterlogged Clay Gardens

If your lawn is under water from November to March, no amount of new turf, aeration or sand will fix it. Water needs somewhere to go, and on Weald clay it will not go downwards on its own. Every successful wet-garden project we have done starts with finding out where the water comes from and where it can legally and practically be taken.

Work out what kind of wet you have

• Surface water from roofs, drives and neighbouring ground running into the plot.
• Perched water sitting on a compacted layer a spade's depth down, common on new-build gardens.
• A genuinely high water table, where the ground is wet because the whole area is.
• A low spot with nowhere to fall to, which is a levels problem rather than a soil one.

The measures that actually work

Land drainage in a herringbone or single-run layout, laid in gravel-filled trenches with a geotextile wrap and falling to an outfall or soakaway, is the workhorse. It only works if it discharges somewhere: a soakaway sized by percolation test, a watercourse where consented, or a surface water connection where one legitimately exists. Alongside it, regrading to create positive falls away from the house, permeable surfaces instead of sealed ones, raised planting beds, and swales or rain gardens on larger plots all reduce the load.

What it costs, as a guide

Guide ranges: a land drainage scheme for an average rear garden commonly falls between £3,000 and £9,000 depending on run lengths, spoil removal and access. A properly sized crate soakaway typically falls between £1,500 and £4,500. Regrading and reprofiling a garden varies enormously with spoil volumes. These are indicative only and depend entirely on percolation results and site access.

Please treat every figure here as an indicative guide range based on projects we have completed, not a quotation. The final price depends on access, ground conditions, levels, drainage and specification, and is only confirmed after a site visit.

The rules worth knowing

You may not discharge water onto a neighbour's land or onto the highway. Soakaways must be a safe distance from buildings and boundaries. Connecting surface water into a foul sewer is not permitted. On new-build plots, the developer's drainage strategy sometimes explains the problem, and it is worth obtaining before designing a solution.

Order of works

Drainage first, levels second, structures third, surfaces fourth, planting last. Gardens built in that order stay dry. Gardens built in the reverse order get dug up again.