Drainage Channel Installation

A drainage channel, sometimes called a channel drain, linear drain or ACO drain, is a narrow grated trough set into paving to catch surface water before it reaches somewhere it should not. If rain is pooling on your drive, running into a garage or sitting against the back door, ring 07427 195142 and we will look at where the water is going and how a channel could take it away.

Where channels make sense

Hard surfaces do not absorb rain. Every square metre of tarmac, block paving or concrete sends its water somewhere, and gravity decides where. A channel intercepts that flow along a line, which a single round gully cannot do.

• Across the foot of a driveway that slopes towards the house or garage
• Along a doorway or patio door threshold
• At the edge of a patio laid without enough fall
• Across a yard or loading area on commercial premises
• Beside a path where water crosses from higher ground

Getting the fall and the outlet right

A channel is only as good as the drain it empties into. The surface must fall towards the channel, the channel must fall towards its outlet, and the outlet must connect to a drain or soakaway that can take the water. Surface water should go to a surface water drain or soakaway, not into a foul drain, and the rules on new hard surfacing are summarised in our guide to drainage regulations in Scotland.

Before any channel goes in, it is worth knowing what the existing pipework is doing. A short CCTV drain survey shows whether the drain the channel will feed is clear and sound. There is no point adding water to a pipe that is already struggling.

Choosing a channel

Channels come in different widths, depths and load ratings. A domestic patio needs something quite different from a driveway that takes a car, and a commercial yard that takes delivery vehicles needs a heavier grade again. Grates vary from slotted steel to cast iron and plastic, and some are designed to sit discreetly in block paving.

The bedding matters as much as the channel itself. Channels set in concrete with the paving finished slightly above the grate edge last far longer than ones laid loose, which tend to rock, crack and let water run underneath.

Keeping channels clear

Most problems with existing channels are not about the channel at all. Silt, grit from block paving, leaves and gravel wash in and settle at the bottom, and the outlet box at the end fills up first. Once it does, water backs up along the grate and spills over, and owners often assume the channel has failed.

Lifting the grates, emptying the silt trap and jetting the outlet pipe usually brings a channel back into use. Doing it before winter avoids the first heavy rain finding the blockage for you. Our drain cleaning and maintenance page covers planned cleaning, and high pressure water jetting explains how silted runs are cleared.

Channels, gullies and land drains

A channel catches water running across a hard surface. A gully catches water from a downpipe or a low point. A land drain deals with water that has already soaked into the soil. They often work together: a drive might have a channel at the bottom, a gully for the downpipe and a land drain along the lawn edge.

If the problem is a soggy garden rather than a wet drive, see our page on land drainage and French drains. If a blocked outside drain is causing the overflow, our drain unblocking page explains how we clear it.

Questions