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ACO Drain Calculator — How Many Channel Drain Lengths Do I Need?
Calculate ACO-style channel drain components including channel lengths, end caps, corners, outlets, gratings and sump units to BS EN 1433.
Total linear length of channel drain
90-degree corners in the drain run
Rule of thumb: ~1 outlet per 10–15m, or at the lowest point. Actual capacity depends on catchment area and rainfall (AD H3).
Price per metre of channel for cost estimate
How We Calculate This
This calculator determines the components needed for a linear channel drainage system based on your total run length, corner and outlet requirements.
The formula
Channel lengths = ceil(Total run length / 1m)
Standard ACO-style channel drain units are 1 metre long. The total run length is divided by 1m and rounded up to determine the number of channel units needed.
Components calculated
- Channel lengths (1m): The main channel body units
- End caps: 2 per system (one at each dead end)
- Corner units: Special units for 90-degree bends
- Outlet units: Connect the channel to underground drainage
- Sump units: Debris/silt collection at each outlet
- Grating positions: One per channel unit plus one per corner unit. Note: standard ACO channel and corner units are supplied complete with a black plastic grating, so you only order gratings separately if upgrading to galvanised steel or cast-iron tops.
Standards
Channel drainage systems must comply with BS EN 1433 (Drainage channels for vehicular and pedestrian areas) which defines loading classes from A15 to F900. The installation should also comply with Part H of the Building Regulations for connection to the drainage system.
Frequently Asked Questions
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Last updated: February 2026
Verified against UK standards · estimates only, confirm with your supplier.