Sort your drainage before winter: French drains, soakaways and the kit to do it

A French drain and soakaway are the two most common fixes for a waterlogged lawn or rain pooling against a house, and late October is a good time to put them in. South Hams ground is still workable and a system dug now will be working before the wettest months. Olympus Plant & Tool Hire delivers the diggers, dumpers and drainage products to do it, from Ivybridge and Modbury to Kingsbridge, Salcombe and Dartmouth.

How can you tell your garden has a drainage problem?

The clearest sign is water still on the lawn a day after rain. Others are moss and rushes in the grass, a damp tide mark on a wall, or a gravel drive washing into the lane.

Two local factors make it worse. Parts of the South Hams sit on dense clay subsoil, which lets water in very slowly, and many gardens are cut into steep slopes, so run-off from higher ground ends up against your house.

French drain and soakaway: what is the difference?

A French drain is a stone-filled trench, usually with a perforated pipe and a geotextile membrane, that collects water from the ground and carries it away on a gentle fall. A soakaway is a pit of rubble or plastic crates wrapped in membrane, which lets water soak slowly into the surrounding ground.

Many jobs use both: the French drain gathers water across a lawn or behind a retaining wall and leads it to a soakaway lower down the garden.

What do Building Regulations say about soakaways?

Rainwater from roofs and paved areas falls under Part H of the Building Regulations (section H3 of Approved Document H). Council guidance based on it says a soakaway should be at least 5 metres from any building, including your neighbour’s, and lower than the area it drains.

Test the ground first. A percolation test, usually following BRE Digest 365, means filling a trial pit with water and timing how fast it drains. On slow clay a soakaway may need to be far larger, or may not work at all. If the work is part of an extension or new driveway, speak to building control first.

Which digger and dumper do you need for a French drain?

For most garden drainage a small machine is enough. The Micro Excavator / Digger 0.75 Ton fits through narrow side gates and onto the terraced plots common in Salcombe and Dartmouth, while the Digger 1.60 Ton or Excavator / Digger 2 Ton digs longer runs and soakaway pits faster.

On a steep plot, moving spoil is often the harder part. A Track Barrow (Diesel) or the Dumper 1 Ton High Lift Dumper carries soil and stone up slopes that would finish off a wheelbarrow, and Ground Mats protect the lawn. Add a 2 inch Submersible Pump for a trench that fills with rain, and Drain Rods to clear existing drains.

We also sell underground drainage products, so pipe and fittings can arrive on the same delivery as your hire.

How do you dig safely around underground services?

HSE guidance HSG47, Avoiding danger from underground services, sets out a safe system of work: get the service plans, locate and mark services with a detection tool, then dig carefully, by hand close to any service.

Hire the Cat4 Scan and Genny Combined and scan the full line of the trench. On rural South Hams properties, private water pipes, oil feeds and old farm cables are often missing from any plan.

When should you call a groundworker?

Call in a professional if water is coming through a wall below ground, a percolation test fails, the drain must join a public sewer, or the trench will be deep or near foundations. Deep trenches can collapse without warning.

How do you hire drainage kit from Olympus in the South Hams?

Our Ivybridge yard is a storage, delivery and admin base only, not open to the public or trade. Call 01752 922535 or email hire@olympushiresouthhams.co.uk for a quote and we will deliver anywhere in the South Hams (Monday to Friday 7.30am to 5pm, Saturday 8am to 10am). To visit a hire counter, use our Newton Abbot store (olympustoolhire.co.uk).

Drainage questions we are often asked

Can a soakaway work in clay soil?

Sometimes, but clay drains slowly, so the soakaway usually needs to be much larger. A percolation test to BRE Digest 365 shows whether it is practical.

What size digger do I need for a French drain?

A 0.75 ton micro digger usually suits a garden with narrow access; a 1.6 to 2 ton digger is quicker for longer runs or a soakaway pit.

Do I need a cable scanner before digging a drain?

It is strongly advised. HSE guidance HSG47 expects services to be located before digging, and a Cat4 scanner with a Genny is the usual way to do it.

Call Olympus Plant & Tool Hire on 01752 922535 to book delivery of a digger, dumper and drainage products to your site anywhere in the South Hams.