Catford Surface Water & Drain Backup (SE6)

TL;DR A gully may overflow or a ground-floor toilet may gurgle during heavy rain. Three different things could be going on. They are river flooding, surface water flooding and a blocked drain. Each needs a different response and different people. In lower-lying parts of Lewisham near the Ravensbourne and the Pool, all three are possible. Check your postcode's long-term flood risk on GOV.UK, find out which pipe is yours, and keep your own gullies and drains clear. If water backs up on a dry day, or only at your property, a blocked private drain is the more likely cause. You can request a quote online for an inspection.

Where Catford sits Catford is part of the London Borough of Lewisham, so Lewisham Council covers it. It sits between Ladywell, Honor Oak and Hither Green. Lewisham Council lists Catford and Catford Bridge stations, Mountsfield Park, Ladywell Fields, the Broadway Theatre and the Glass Mill Leisure Centre under Catford. Catford Bridge station is SE6 4RH, and Catford station sits at Ravensbourne Park, SE6 4RW.

Ladywell Fields runs between Catford and Ladywell, and the River Ravensbourne flows through it. The park is around a mile long. The Waterlink Way follows the Ravensbourne and Pool rivers, and the two rivers flow into the Thames at Deptford Creek. The Waterlink Way is National Cycle Network route 21.

A short, sourced flood history On 15 September 1968, much of Lewisham flooded, although the river had been quiet before. Since then the Environment Agency has worked on plans to manage flood risk from the Ravensbourne in Lewisham and Catford. It calls this the Lewisham and Catford flood alleviation scheme.

Lewisham's 2017 Preliminary Flood Risk Assessment gives a useful picture of the wider borough. It names the Ravensbourne corridor as a critical surface water drainage catchment. It notes that areas with known flooding problems also lie in Flood Zone 3.

It also says the lower-lying areas around the Ravensbourne, Pool and Quaggy face the biggest rise in people at risk under climate change. It refers to development along the river between Catford and Lewisham too.

None of this tells you whether your own drain will back up. However, it explains why lower-lying homes notice more when the public drain network is busy.

Three different problems that look alike

River flooding River flooding happens when a river such as the Ravensbourne rises over its banks, while a drain blockage has nothing to do with rivers. Flood Zone 3 is the Environment Agency's name for land with a high chance of river or sea flooding. A drainage contractor cannot stop a river rising.

Surface water flooding Surface water flooding happens when rain falls faster than the ground and drains can clear it, because water has nowhere to go. Water runs along roads and paths and collects in low spots, often far from any river. The 2017 assessment's critical surface water drainage catchment is about exactly this. Hard surfaces send rain into gullies and sewers fast. When the network is full, the water has nowhere to go.

A blocked private drain A blocked drain is a blockage inside the pipes that serve your property, whereas the other two start outside. It can happen on a dry day in July as easily as in a storm. Typical causes are fat, wipes, debris, tree roots or a displaced section of pipe. Heavy rain can make a partial blockage much more obvious, because the pipe must carry more water than it can pass.

How a busy sewer pushes water back up Many older parts of London have combined sewers, since they were built long ago. These carry foul water from toilets and sinks, and also rainwater from roofs and roads. In a very heavy downpour, the sewer can fill up. When the main pipe is full, water from the private drains that feed it cannot get out, so it rises instead. People call this surcharge.

The water finds the lowest openings it can reach, because it cannot go up. These include the gully in the yard, a shower tray, a ground-floor toilet or a chamber cover. So the first signs are often gurgling from a sink or slow draining across several fittings. A smell from a gully is another clue.

Suppose the same fittings back up whenever it rains hard, and they clear again afterwards. The problem is then likely to be capacity in the wider system, because your own pipes are fine. However, if they are slow in dry weather too, look at your own drain first. The same goes if only your property suffers while the neighbours are fine.

Check your postcode's flood risk GOV.UK has a free service called Check long term flood risk, although it covers areas, not single pipes. Anyone can use it by entering a postcode. It shows the long-term risk from rivers, the sea and surface water. It will not tell you if a particular pipe has a blockage. Still, it gives a background picture of how exposed your street is to flooding.

Who owns which pipe Ownership matters, because it decides who you call and who pays.

Thames Water became responsible for private sewers and lateral drains from 1 October 2011. Homeowners remain responsible for the pipe between their property and the transferred section. In practice, that usually means the following:

Your own pipes, gullies and chambers inside your boundary are your responsibility. A blockage here is a job for a drainage contractor.
A shared pipe that serves several properties, or the lateral drain beyond your boundary, may now sit with Thames Water. If you are not sure where your duty ends, ask Thames Water before you pay for work on a shared or boundary section.
Public sewers and road gullies are the water company's and the council's concern, not yours.

Here is a simple test, since the pattern tells you a lot. If one property suffers and the blockage is near the house, start with your own drain. If several neighbours suffer at once, or water surfaces in the road, report it to Thames Water.

Practical steps to reduce the risk - Keep gullies and grids clear. Leaves, silt and litter collect in yard gullies, and they can stop surface water reaching the drain at all. Check them before heavy rain is forecast, and wear gloves. - Do not pour fat or oil down the sink. It cools and sets in the pipe, and then it catches other debris. - Bin wipes, even those labelled flushable. They do not break down like toilet paper, and they are a common cause of blockages. - Know where your inspection chambers are. Keep the covers easy to reach. Lifting one shows you whether water is flowing or standing, which helps anyone you call.

Telling a private blockage from a sewer problem Look at the pattern, not just the symptom.

Some signs point to a blockage in your own drain, while others point to the wider sewer. Drainage may be slow in dry weather. One fitting or one run of pipe may show the fault.

A chamber may be full while the next one downstream is empty. The problem may return after you clear it.

Other signs point to the wider sewer. Several neighbours may suffer at the same time. Backing up may happen only during or just after heavy rain. Water may rise in more than one low fitting across the property.

If you cannot tell, a CCTV drain survey can help, because the camera shows the pipe itself. A camera sent along the pipe shows what is really inside. It may find debris, roots in a joint or a displaced section.

It may also show a clear pipe that is simply running full because of what happens downstream. A survey of your private drain also gives you something concrete to show Thames Water, if the problem lies outside your boundary.

Local pages and what to do next Our Catford page covers how we work on blocked drains in Catford, and the services there. Our Lewisham coverage page covers the wider borough.

If your drain keeps backing up and you are not sure why, request a quote online. Tell us the symptoms, when they happen and whether the neighbours have the same trouble. That detail helps us work out whether it looks like a private blockage, a shared pipe or something to report to Thames Water.