French Drains: Do They Fix a Waterlogged Garden?

A French drain is a gravel-filled trench with a perforated pipe in the bottom that collects excess water from the soil and carries it away. It can fix a waterlogged garden, but only when the water has somewhere lawful to go and can reach the trench through the soil. Installed, French drains typically cost around £200 per metre, according to MyBuilder's 2026 price guide.

Before you dig, it pays to work out why the garden is wet in the first place. This guide covers how French drains work, where they help, where they don't, and what else could be causing the problem.

What is a French drain?

A French drain is a shallow trench lined with a permeable geotextile membrane, part-filled with clean gravel, with a perforated pipe laid along the bottom. The membrane is folded over the top of the stone, then the trench is finished with more gravel, topsoil and turf, or a decorative surface.

Water in the surrounding soil moves into the gravel, because it is the easiest path, and enters the pipe through the perforations. The pipe is laid to a steady fall so the water runs to an outlet, such as a soakaway, a ditch or an approved drain connection.

The key components are:

• a fall, so water keeps moving towards the outlet instead of sitting in the pipe;
• a geotextile wrap, which stops fine soil washing into the stone and clogging it;
• clean, free-draining stone, which gives water an easy route to the pipe;
• an outlet that can accept the water, even in prolonged wet weather;
• an access or rodding point, so the pipe can be inspected and jetted later.

When will a French drain help?

A French drain works best where water is moving through the upper layers of soil and simply needs a route away. Typical examples include:

• a lawn at the bottom of a slope that stays soggy after rain;
• water running off higher ground towards a house, patio or outbuilding;
• ground behind a retaining wall that stays saturated;
• a path or patio edge where water collects and will not clear.

In each case the trench intercepts the water before it reaches the problem area and carries it somewhere that can cope with it. French drains are often combined with other measures, such as regrading a lawn so water runs towards the trench, or redirecting a downpipe that has been discharging onto the grass.

When won't a French drain work?

A French drain is not a cure-all. It is likely to disappoint where:

• the soil is heavy clay, because water moves through clay so slowly that little of it reaches the trench;
• there is nowhere to discharge, because the drain will simply fill up and stay full;
• the water table is high, so the outlet is as wet as the garden for much of the winter;
• the problem is surface compaction, where aerating and improving the soil may do more good;
• the water comes from a leak, such as a broken drain, a failed soakaway or a downpipe discharging onto the lawn.

Springs and persistent seepage lines can sometimes be managed with land drains, but they need a proper assessment of where the water comes from and where it can go.

Where can the water from a French drain go?

The outlet is a critical design decision, and it is easy to overlook. The usual options are:

Around Nottinghamshire and most of Derbyshire and Leicestershire, the sewerage company is Severn Trent; most of Lincolnshire is Anglian Water. Our guide to soakaways explains infiltration testing and why clay can rule a soakaway out.

Wherever the water goes, avoid simply moving the problem onto a neighbour's land. Redirecting water towards another property can cause disputes and damage.

What else causes a waterlogged garden?

It is worth ruling out other causes before paying for a French drain:

• compacted soil, often after building work or heavy use, which stops rain soaking in;
• downpipes discharging onto the ground, or a soakaway that has silted up;
• a leaking or broken underground drain, which can leave persistently wet patches or a strip of greener grass along the pipe run;
• changes to ground levels, including a neighbour's new patio or driveway;
• more hard surfacing, which sends more water to the remaining soft ground.

Hard surfacing matters at street scale too. Nottinghamshire County Council's report into flooding in Mansfield on 10 June 2016, when 64 mm of rain fell in 24 hours and 17 properties flooded, pointed to paved-over front gardens as a factor.

If you suspect a leaking drain, a CCTV drain survey will show whether the pipe is cracked or broken before you spend money on garden drainage.

How much does a French drain cost?

Costs depend on length, depth, access for a digger, spoil removal and the outlet. MyBuilder's guide (21 August 2026) gives these typical figures:

Treat these as national market ranges rather than our prices. A new soakaway, a connection to an existing drain or reinstating paving on top will add to the total. We give a written price after seeing the site, and it is agreed before work starts.

Can you install a French drain yourself?

A short, shallow run is a feasible DIY project if you are fit and careful, but the details decide whether it works. The pipe needs a consistent fall, the membrane must wrap the stone properly, and you will have a lot of spoil to move.

Before digging:

• check for buried cables and pipes using LinesearchbeforeUdig and any plans you hold;
• keep away from foundations, and do not dig deep trenches next to walls;
• never enter a deep trench with unsupported sides, because they can collapse;
• confirm the outlet is lawful and can take the water before you start.

When to call a professional

Get professional help if the waterlogging is close to the house, the trench would be deep, you are unsure where the water can go, or you suspect a broken drain. Our groundworks team installs French drains, land drainage and soakaways across Nottinghamshire, Derbyshire, Leicestershire and Lincolnshire, and can camera-survey existing drains first so you fix the real cause.

There is no call-out fee and the price is agreed before we start. Contact us or call 07300 600 950.

Sources

• MyBuilder: French drain cost guide
• Approved Document H: Drainage and waste disposal (gov.uk)
• gov.uk: Flood risk activities and environmental permits
• Nottinghamshire County Council: Mansfield Section 19 flood report (2016)
• LinesearchbeforeUdig