A drain that works all summer can fail in the first big storm. Water rises in the gully, backs up in the garden or even comes up inside the house. Heavy rain does not always cause the fault. However, it often shows a weakness that was already there.
This guide explains what happens when it rains hard. Specifically, it covers what you can check and when to call a drainage engineer.
What Surface Water Flooding Means
The government describes surface water flooding as flooding that happens when the volume and intensity of rainfall overwhelms local drainage systems. The rain then lies on or flows over the ground instead of draining away. It can happen far from any river, because it starts with rain falling on built-up ground.
Paved drives, patios and roads make this worse, because rain cannot soak in. Instead, it runs to the nearest gully or drain. If those are full of silt and leaves, the water has nowhere to go.
Combined Sewers in Chester
Many older towns have combined sewers, which carry both foul water and rainwater in one pipe. In heavy rain, the pipe can fill quickly.
Cheshire West and Chester Council describes a rainwater drainage tunnel under the city. According to its news page, the tunnel is meant to cut discharges into the Dee from the old combined sewerage system.
Although we cannot say what happens on your street, a council study of the area noted sewer flooding incidents in Chester and recommended a surface water management plan for the city. That does not tell you about your street. It does show that drainage capacity is a known issue in the area.
The River Dee and High Tides
While the River Dee is normally tidal up to Chester Weir, according to the Environment Agency's River Dee flood plan. On spring and extreme tides, the tidal influence can reach as far upstream as Shocklach. The Environment Agency publishes flood warning areas for the tidal Dee at Chester, such as the one at Hawarden Embankment.
This matters for drains because a high river can slow the way outfalls empty. If you live near the river, check the official flood service for your address. We cannot tell you whether your property is at risk. The flood service can.
Common Causes of Drains Backing Up in a Storm
Several faults show up when the rain is heavy. Some are simple to fix, yet others need a closer look. Others need a closer look.
- Gullies and grates blocked with leaves, silt and litter
- Roof gutters and downpipes full of debris
- Fat, wipes or roots already narrowing the pipe
- Collapsed or displaced sections that cannot carry the extra flow
- Surcharged public sewers during heavy storms
Because of this mix, it pays to find out which one you have. Our guide to the signs of a blocked drain helps you spot the early warnings.
What to Check Before the Next Storm
A little upkeep goes a long way, because most storm faults start small. Clear leaves from gutters and from the gully near your downpipe. Also lift any grating you can reach and remove the silt that has built up.
Next, look at your patio and drive. Water should run away from the house, not toward it. For example, a drive that slopes to the front door will send storm water straight to the threshold.
Finally, make sure that grease and wipes are not going down the kitchen drain. Our post on how to prevent blocked drains in your kitchen covers this.
Who Looks After the Road Gully
Roadside gullies are the council's job, not yours, and a gully can still fill between visits. You can report a blocked road gully to Cheshire West and Chester Council through its website. If the water is on your own land, the drain may be yours to deal with.
Our guide on who is responsible for drains in Chester explains how to tell the difference. Do this before you pay for work on a pipe that is not yours.
What to Do During and After a Storm
During a storm, keep safe and stay out of floodwater, because it can carry sewage and is not safe to touch. Move valuables up and switch off any electrics that are at risk if it is safe to do so.
After the storm, look for slow drains, bad smells and damp patches. These can show a pipe that took damage. Where water floods back into the house, follow our steps in emergency drain problems.
When to Call a Drainage Engineer
Call us when a drain fails more than once in wet weather. A repeat fault points to a cause that clearing alone will not fix. A CCTV drain survey shows the pipe from the inside. It can reveal cracks, roots or sagging sections that make a drain struggle under load.
For example, for a clogged line, drain jetting can wash out silt and debris. If sewage is coming back into your home, treat it as urgent and see our emergency drain services. Otherwise, send us the details through our contact page.
