In the 1850s work began in London to create a giant sewage network to try and rid the capital of waste that was causing major outbreaks of cholera along the Thames and leading to a huge number of deaths.
It was one of the biggest infrastructure projects of the time and was led by renowned engineer Sir Joseph Bazalgette (pictured right).
It proved a huge success and remains a vital component of London today by helping to remove tonnes of effluent from the capital. But there are other, more modern benefits, too.
By building thousands of miles of sewage tunnels under the city – as much as 67,000 miles according to Thames Water – there is a network that is ideally suited to running fibre optic cables through the heart of London.
This is exactly what Geo Networks uses to run its services around London. Last week it announced that it had used the sewer network to help it reduce the length of connections between east and west London by 43km, which helped it reduce latency and offer better network diversity in the capital.
Clipped to the inside of around 300km of the underground tunnels are high-speed fibre optic cables that help carry network traffic freely through London, rather than having to loop around the edge of the city, as most other networks do.
The CEO of Geo Networks Chris Smedley (pictured below), told V3 that the firm has been able to do this because it has a relationship with Thames Water, since it bought the firm out of a joint venture to deliver internet services.
“About eight years ago we bought a business from Thames Water, a subsidiary then known as Lattice Plc, which included the network assets already in place, and so we’ve always had a relationship,” he said.
“This means we are able to work to plan rollouts and put them in place in a few weeks, rather than having to dig up roads. They [Thames Water] are comfortable with our operational arrangement and how we work together."
Smedley said that for many businesses, Geo’s use of the sewers is seen as a big selling point because it provides another network route, to help provide backup and resilient capabilities.
“Most Geo customers are concerned about performance and uptime. Because we go through the sewers we take out a lot of these risks and can move data faster direct through the city,” he said.
“Some customers want three or four routes, not just for their business but for specific applications.”
The other benefit for Geo is that not many other providers have the means – or desire – to start building their own networks underground, or to try and negotiate deals similar to the one it already has with Thames Water.
As such, a sizeable portion of its business comes from the leasing of lines to other providers or large enterprises, to provide their own lines.
“Because we have such a good wholesale proposition most other customers are happy to be our customers and we serve almost every other carrier business so they can deliver services onward to their customers,” he said.
The cables themselves are run along the ceilings of the sewers, as you can see in the images, to keep them clear of the water and its contents. Smedley boasts that the network remains highly resiliant as a result, having never suffered an outage.
Annelise Berendt, telecoms analyst at Point Topic, told V3 that Geo's ability to avoid any surface disruption when accessing or enhancing its network is key to its success.
"Geo was innovative in its use of the London sewers fairly early on," she said. "[It] certainly seems to have been successful in leveraging a cost-effective and faster approach to fibre deployment, compared with digging, in the crowded urban environment that is London."
Smedley attributes part of the success that Geo has had to its close working relationship with Thames Water, which means both firms trust one another and there is good communication when any work needs doing.
So while the idea of wading into a London sewer is not high on the agenda for most, for Geo, it's all part of the job when anything needs checking, or new fibre needs installing to help boost the capital's internet. Bazalgette would be proud.