Stinky business: south London bike shop hit by ‘unbearable’ stench from Thames Water sewer

The leafy south London neighbourhood of Herne Hill is a haven for cyclists who can often be seen lapping the local parks and refuelling at the many cafes that line the suburban streets. But there is something foul in the air of this corner of the capital – and for once it’s not the traffic fumes hitting bicycle riders.

A toxic stench thought to be caused by untreated sewage stuck in Thames Water drains has been emanating from the subterranean depths for months, most likely caused by the summer’s lack of rain.

The stink is so acrid that the Bicycle Nation shop has had to bar some customers and its mechanics have been forced to work on the pavement outside.

The owner of the shop, Tamas Polocz, has repeatedly complained to Thames Water since the smell first hit the shop in June and caused his colleague Nick to vomit.

Last week the troubled water company told Polocz it accepted that a mains sewer directly beneath the shop was to blame, but it has yet to offer him and his team of 11 any date for resolving the problem.

Polocz and his colleagues have been left fearing for their physical and mental health after repeated exposure to the gassy stench. And the outlook for the business is bleak.

The odour comes in putrid wafts that occur at least five times a day, according to a “smell chart” used to log the time and duration of each incident with a description. The words used include “cabbage”, “teargas”, “onions”, “spicy BBQ” and repeated references to “shit”.

When the Guardian first arrived at the shop there was a whiff of rotten eggs but not enough to stop mechanics working inside and customers milling about. But within minutes we were overpowered by a repulsive gas that hit the back of the throat and left us scurrying outside, gagging for air.

“It’s unbearable,” said Polocz. “You can’t be in the shop when it comes.”

He added: “It has a really strong physical presence. This is a smell you take home with you. It’s in your hair, on your skin, sometimes it feels it’s inside your skin. When you go home and cough, you taste it again.”

The ordeal comes after record-breaking temperatures and drought prompted calls for a radical overhaul of an outdated sewage system, just as the Great Stink ushered in new sanitation in the Victorian era.

Thames Water initially suggested the Herne Hill smell was due to a gas leak. But extensive tests by the local gas supplier ruled that out.

Polocz said he had been battling the company every week. “Thames Water have always tried to push me away, or blame others. When they finally accepted liability last week I just broke down. But we still don’t have a date for fixing it.”

The exact cause of the stench remains unknown, but a Thames Water engineer told Polocz it was likely to be linked to the lack of rain. The engineer also told him that a cast-iron ventilation pipe that had previously drawn odours away from the shop had not been replaced.

Experts warn that during dry periods, untreated sewage builds up in pipes with no rainwater to flush it out. Microbial activity in the sewage causes foul-smelling gas to be emitted in wafts, in a similar process to the one that causes flatulence in human digestion.

Prof Barbara Evans, the chair of public health engineering at Leeds University, said: “It sounds like methane and it’s probably unsafe working conditions. Biological processes are cyclical just like in your digestive system, which is why sewer smells come in wafts.”

When Polocz woke up to rainfall, he was hopeful it would flush away the stench. “I looked out through the window at home and thought, oh good, but it didn’t make any difference. Even after the rain there was still the smell. Maybe the rain will eventually clear it, but we don’t know. Something is happening down there that is pushing the smell up.”

Evans said: “The first flushes of rain will probably make things smell worse because it just stirs things up. It needs a lot of rain to clear. There might be some blockage there but it’s impossible to know without a proper inspection.”

Harriet Talbot, a board member of Bicycle Nation, said: “You can’t run a business relying on the weather.” She helped set up a webpage asking for customers to sign up for a collect and repair service to help the shop survive.

Polocz said the shop was currently unsustainable because staff had to evacuate so frequently. “We have to do half a day in the shop and half outside on the pavement. But now the cold weather is coming, we can’t keep doing that.”

And the stress from the stink is taking its toll. Polocz said: “I’m 49, but today I feel 62-ish. We have guys calling in sick. It affects you both physically and mentally.”

Polocz said he laid in bed at night worrying how he would be able to keep the shop going. “The last thought of the day and the first thought of the day are now both the same,” he said. “And I wake up at night thinking: what are we going to do about it? I try to listen to a podcast, but I still keep thinking about the smell. Somehow I’m going to get through this and change back to normal.”

Polocz’s plight is likely to add to calls for an overhaul of London’s Victorian sewage system. Evans said: “This underlines the need for a rethink of our sewers. The system was designed for a climate that we just don’t currently have any more.”

The Guardian asked Thames Water when the problem would be fixed, why it had taken so long to resolve, and whether the company would apologise to Polocz.

A spokesperson replied: “Our teams are investigating the source of an odour reported at a bike shop. Initial investigations have confirmed there are no blockages in the sewers surrounding the property. Odour monitors are to be installed, which will enable engineers to detect, measure and track odorous gases in real time and help determine the exact cause.”