Not all flooding can be prevented. But a large share of the surface water flooding we are called to in the South West does not start with an exceptional storm — it starts with a gully that has not been lifted in five years, a silted culvert, or a downpipe discharging onto a path instead of into a drain. Those are all fixable, and they are usually cheap compared with what happens when they are not.
Why drainage is the part you can actually control
Rainfall, river levels and tides are not within anyone’s gift. The capacity of the system that takes water away from a building is. A drainage network silted to half its bore carries roughly half the water, and it fails at exactly the moment it is needed most. Most properties that flood repeatedly are not unlucky; they are draining through a restriction nobody has measured.
The checks worth doing before the autumn
- Lift every gully grid. Clear the leaves, grit and silt out of the trap. Do it at the end of the summer and again after leaf fall.
- Follow your downpipes. Every one should end in a gully or a drain, not on a slab or in a border. A surprising number do not, and it is often the cause of damp as well as flooding.
- Clear the gutters. Overflowing gutters put water down walls and into foundations rather than into the drainage system. See gutter and surface cleaning.
- Check catchpits and interceptors. On yards, car parks and access roads these fill with grit and stop working silently.
- Look in the chambers. Standing water in a manhole when nothing is discharging means a restriction downstream.
- Know where the water goes. If nobody on site can say where the surface water discharges to, that is the first thing to establish.
Culverts, ditches and watercourses
If a watercourse runs through or under your land, its condition is very much your problem. Culverts silt up, grilles block with debris, and headwalls fail — and the first anyone knows about it is water backing up across a field or a road. Where a culvert cannot be walked, it can still be surveyed: we surveyed over a kilometre of culverted watercourse for AECOM on the Siston and Warmley flood defence scheme using steerable CCTV and a confined space entry team, so the hydraulic modelling was based on measured silt levels rather than assumptions.
Riparian owners have legal responsibilities for maintaining flow. If you are not sure whether that applies to you, the Environment Agency publishes guidance for riparian owners, and it is worth reading before rather than after a flood.
Protecting the building itself
- Non-return valves. Where a property has flooded from the drainage system rather than from outside, a non-return valve on the outgoing connection stops sewage coming back up through the lowest fitting. This is a common fix in basements and low-lying ground-floor conversions.
- Raise what you can. Consumer units, boilers and sockets above the likely water line, and solid or replaceable floor finishes at the lowest level.
- Airbricks and thresholds. Covers and barriers are inexpensive and only work if they are on site before the water is.
- Sign up for flood warnings. The Environment Agency’s free flood warning service gives you the hours that make the difference.
When water is already rising
Safety first: never walk or drive through moving flood water, and treat any flooding that may contain foul drainage as a health risk rather than an inconvenience. Turn off electricity at the consumer unit if it is safe to reach. Photograph everything before you move it — insurers will ask.
Standing water can be recovered to tanker rather than pushed somewhere else, which matters when it is contaminated. Our jetvac and tankering units are available around the clock on 0800 328 6655, and emergency drainage help sets out what happens when you call.
Afterwards: find out why
Once the water has gone, the useful question is what restricted the system. A CCTV survey of the runs that surcharged will normally show it — a collapse, a displaced joint, root ingress, or simply years of silt. Putting that right, and then putting the system on a planned maintenance schedule, is what stops the same week repeating next winter.
Talk to Exjet about your drains
Exjet Services has been solving drainage and sewer problems across Devon, Cornwall, Somerset and Dorset since 1986, with commercial and planned work right across the South West. Our engineers are directly employed, and we are certified to ISO 9001, ISO 14001 and ISO 45001.
Related services: commercial sewer cleaning, tankering, gutter and surface cleaning and planned drainage maintenance.
Blocked now? Ring 0800 328 6655 — answered any hour — or request a quote.