I thought people might be interested in how a story such as this one comes together... back in April we published a piece looking at the specific issue of misconnections in one corner of London. But the volunteers working on the River Brent and River Crane in west London, who have been doing the leading work highlighting this issue, say it was hard to make people comprehend the scale of the problem.
The issue is you just see stories about "thousands of properties leaking sewage" and none it feels real.
I challenged Rachel Rees, who spent most of this year working for London Centric, to find a single example of a misconnected pipe and trace its journey through the capital. This became one of the most infuriating projects we've done. Endless formal requests for information, tracing underground rivers, trying to convince authorities that we are trying to highlight an issue and get individuals to confront it. She had to put up with constant nagging from me to keep going. Eventually she found this location in Crouch End and managed to follow its journey across north and east London.
All in all this was an absolutely crazy amount of work over eight months to bring this single story to life.
Rachel has since left to join a niche news publication called the "Financial Times", having picking up a nomination for young journalist of the year for her work with London Centric. So this is probably her final byline here — and it's one of those that I'm really proud to publish.
Great work, Jim and Rachel. I will admit I did initially read that as "Rachel Reeves" (I'm sure she's never heard that one before) and thought "Doesn't she have enough on her plate?"
Another magnificent article on this little-known but pressing issue for London's rivers. CURB - Clean Up the River Brent, and FORCE - Friends Of the River Crane Environment are grateful for the diligent and imaginative coverage LondonCentric has been giving this story. We won't have the Mayor's noble dream of Clean & Healthy Rivers without this problem being resolved. To get to that point, four things have to happen:
1 - our building culture, including inspections, needs to improve
2 - correct drainage needs to go into the material information required to sell a property
3 - water companies need to increase and target their investigative programmes
4 - local authorities need to take enforcement action against outstanding cases
Is this too much to ask?
Thanks again for the work you have put into these stories. You're always welcome to get the waders back on and join us in the Brent. It can be a beautiful place to spend a few hours. Much like this substack.
Great question. Work out which river catchment you live in. Rivers are not just neat blue lines on maps, no-go areas between useful and exploitable land, they are entire territories of rainfall. We all live in rivers. Wherever we are. Have a look at the water in your river, have a smell of it, listen to it, join a river action group, try to think about all the water in your life, and how you interact with it, share what you see and smell and think.
I may be wrong, but judging by the photo and the map, I think the point where the Moselle flows in to the Lea may be in Markfield Park. If so, it's close to this:
- one of the first sites in the city's modern wastewater-treatment system. Which is either apt or ironic, or possibly both. I'd not heard of the place until earlier this year when a friend suggested we visit. It's fascinating and highly recommended, especially on one of the days where the engine is working.
Thanks for taking the time and trouble to reply, Rachel - really good of you. And hearty congratulations on the new job (though you will be missed here).
Thinking about it further, I was probably wrong to call it ironic. Maybe it's inevitable! Given that the pumping station was one of the earliest nodes in the wastewater system, all the earliest sewers across a whole swathe of that part of north London would likely have been connected to it. According to the museum website, waste was treated there until the 1960s, so anything built before then presumably had (has?) a pipe leading to Markfield Park.
This article really struck me, particularly the idea of misconnections as a form of constant, low-level pollution that’s almost designed to evade detection.
It made me wonder whether this is a problem better approached the way lightning monitoring has been: not with a few perfect sensors, but with many cheap ones.
I’ve written a follow-up exploring the idea of a citizen-science sewage monitoring network built around simple ESP32 devices — and, crucially, a London-wide schools project that could combine education, data and river recovery (with water companies as sponsors rather than adversaries).
Important piece. Is there any data on whether this is something that’s solely new buildings that are the main cases, or are things like loft conversions that are part of this - where the plumbing may need to run in pipes to the sewage system separate from the rest of the property
Bit of a mix. In theory should be pretty hard for a new build to manage it but very much does happen.
With an extension you can see how it happens - stick a new bathroom on the back, you’re on a budget/builder is dodgy, they plumb it in and the issue becomes someone else’s problem.
Happened to a friend recently. New downstairs loo and extension. A few months later all the houses in the area with recent planning applications get a letter. They went to each recently installed loo and flushed dye down it to find the culprit. He was the unlucky one. Builders had to dig up the floor to fix it, but at least they did it!
Thank you for writing this. About 10 years ago I ran community festivals in Tottenham, including the River Fest in Lordship Rec to highlight issues & pollution of our rivers, linking up the west & east of the borough. We tried constantly to get answers about misconnections, central to the message we shared. It was impossible to get anyone from Haringey to come to the festival. There always seemed to be a lot of finger pointing & resignations if memory served. Theo Thomas was always great. Good to know the London Waterkeeper is going strong.
The beam engjne in Markfield park is run by a team of enthusiastic volunteers who open it for steam days several times a year.
Thames Water (in London at least) identifies properties that are misconnected, and writes to homeowners to let them know (then goes to councils if homeowners don’t fix it).
But it’s inevitably a hugely undiscovered problem — the process of finding misconnections is so long winded, and depends on volunteers literally wading through local waterways, like Ben from Clean Up the River Brent, who we spoke to for the article we did on this topic back in April or so. That’s why there’s such a mismatch between the reported numbers of misconnections and the much, much higher estimated real figures (eg Thames Water’s estimate that 1 in 10 properties in the area it covers are misconnected)
If you're feeling adventurous, you can tip some harmless food dye down your drains, and see if it turns up in your local river. Otherwise, depending on where you live, your gutters should go into a different drain from your kitchen sink etc. Unless you're in the centre of an old city.
A saying I remember from one of the displays at the Markfield Beam Engine is "Highgate's rain is Tottenham's pain" but this seems to be considerably worse...
Thank you to Rachel Rees for your info re. sewage system zones. We are in Tolworth (very outer suburb) which is in the catchment area of the Hogsmill River. Our house is in a development built around 1907 and I would dearly like to know if we have separate or combined sewers. We lived in a Philadelphia neighbourhood also built around 1907. Most houses had separate sewers but some had to be corrected. I led a campaign to unearth the relevant info. from many disparate government offices. Friends of the Monoshone was our name . We used water samples at each connection to identify the culprit(s), coloured a map of the whole area to demonstrate the stats' implications, and shamed the Water Dept who had failed to act on their own stats.
Here's another idea: dig rain gardens so far less rainwater gets into the pipes but goes straight into the aquifer.
One quick technical point: dissolved oxygen is vital to aquatic life. Nutrients from sewage reduce DO, using it as part of their decomposition, so polluted water is associated with low DO, not high. A significant pollution event will crash oxygen to zero, and everything in the river will die. We have seen this multiple times on the Brent. Healthy, moving water, with low pollution, and a plenty of plant life, will have high levels of dissolved oxygen.
I thought people might be interested in how a story such as this one comes together... back in April we published a piece looking at the specific issue of misconnections in one corner of London. But the volunteers working on the River Brent and River Crane in west London, who have been doing the leading work highlighting this issue, say it was hard to make people comprehend the scale of the problem.
The issue is you just see stories about "thousands of properties leaking sewage" and none it feels real.
I challenged Rachel Rees, who spent most of this year working for London Centric, to find a single example of a misconnected pipe and trace its journey through the capital. This became one of the most infuriating projects we've done. Endless formal requests for information, tracing underground rivers, trying to convince authorities that we are trying to highlight an issue and get individuals to confront it. She had to put up with constant nagging from me to keep going. Eventually she found this location in Crouch End and managed to follow its journey across north and east London.
All in all this was an absolutely crazy amount of work over eight months to bring this single story to life.
Rachel has since left to join a niche news publication called the "Financial Times", having picking up a nomination for young journalist of the year for her work with London Centric. So this is probably her final byline here — and it's one of those that I'm really proud to publish.
Great work, Jim and Rachel. I will admit I did initially read that as "Rachel Reeves" (I'm sure she's never heard that one before) and thought "Doesn't she have enough on her plate?"
She's working for the Financial Times now, imagine how much chaos it causes.
She was also, an hour ago, nominated for 'young local journalist of the year' at the regional press awards for her work for London Centric, so hurrah.
Great reporting thank you! It‘s exactly stories like this one which show why London needs proper news reporting.
Another magnificent article on this little-known but pressing issue for London's rivers. CURB - Clean Up the River Brent, and FORCE - Friends Of the River Crane Environment are grateful for the diligent and imaginative coverage LondonCentric has been giving this story. We won't have the Mayor's noble dream of Clean & Healthy Rivers without this problem being resolved. To get to that point, four things have to happen:
1 - our building culture, including inspections, needs to improve
2 - correct drainage needs to go into the material information required to sell a property
3 - water companies need to increase and target their investigative programmes
4 - local authorities need to take enforcement action against outstanding cases
Is this too much to ask?
Thanks again for the work you have put into these stories. You're always welcome to get the waders back on and join us in the Brent. It can be a beautiful place to spend a few hours. Much like this substack.
How can one help?
Great question. Work out which river catchment you live in. Rivers are not just neat blue lines on maps, no-go areas between useful and exploitable land, they are entire territories of rainfall. We all live in rivers. Wherever we are. Have a look at the water in your river, have a smell of it, listen to it, join a river action group, try to think about all the water in your life, and how you interact with it, share what you see and smell and think.
Really excellent work. I wonder if Feargal Sharkey has read this?!
Here he was on the Brent earlier this year:
https://www.youtube.com/shorts/tegLA-LDJPk
Nice one! I should have known he'd be all over it!
Excellent journalism, a sincere thank you for this.
Yet more excellent work. Thanks hugely.
I may be wrong, but judging by the photo and the map, I think the point where the Moselle flows in to the Lea may be in Markfield Park. If so, it's close to this:
https://www.mbeam.org/
- one of the first sites in the city's modern wastewater-treatment system. Which is either apt or ironic, or possibly both. I'd not heard of the place until earlier this year when a friend suggested we visit. It's fascinating and highly recommended, especially on one of the days where the engine is working.
Yes, it is in Markfield Park! That’s very ironic, thanks for flagging, I hadn’t known about the history
Thanks for taking the time and trouble to reply, Rachel - really good of you. And hearty congratulations on the new job (though you will be missed here).
Thinking about it further, I was probably wrong to call it ironic. Maybe it's inevitable! Given that the pumping station was one of the earliest nodes in the wastewater system, all the earliest sewers across a whole swathe of that part of north London would likely have been connected to it. According to the museum website, waste was treated there until the 1960s, so anything built before then presumably had (has?) a pipe leading to Markfield Park.
This article really struck me, particularly the idea of misconnections as a form of constant, low-level pollution that’s almost designed to evade detection.
It made me wonder whether this is a problem better approached the way lightning monitoring has been: not with a few perfect sensors, but with many cheap ones.
I’ve written a follow-up exploring the idea of a citizen-science sewage monitoring network built around simple ESP32 devices — and, crucially, a London-wide schools project that could combine education, data and river recovery (with water companies as sponsors rather than adversaries).
Here’s the piece if anyone’s interested:
👉 https://richardvahrman.medium.com/listening-to-londons-sewers-549e596a69be
Thanks for shining a light on a problem that’s literally underground.
Hi Richard, CURB is building just such a network on the Brent. You can view our results at yourriver.co.uk
Happy to discuss further!
Very interesting - and pleased to see something is already being done. If something was ever being considered as a school project, would be happy to lend a hand. In the meantime - https://www.brighton.ac.uk/news/2025/brighton-scientists-to-pioneer-dna-based-forensic-tool-to-trace-sources-of-water-pollution - looks promising
Important piece. Is there any data on whether this is something that’s solely new buildings that are the main cases, or are things like loft conversions that are part of this - where the plumbing may need to run in pipes to the sewage system separate from the rest of the property
Bit of a mix. In theory should be pretty hard for a new build to manage it but very much does happen.
With an extension you can see how it happens - stick a new bathroom on the back, you’re on a budget/builder is dodgy, they plumb it in and the issue becomes someone else’s problem.
Happened to a friend recently. New downstairs loo and extension. A few months later all the houses in the area with recent planning applications get a letter. They went to each recently installed loo and flushed dye down it to find the culprit. He was the unlucky one. Builders had to dig up the floor to fix it, but at least they did it!
Fair play to that council, bad luck to your mate!
Thank you for writing this. About 10 years ago I ran community festivals in Tottenham, including the River Fest in Lordship Rec to highlight issues & pollution of our rivers, linking up the west & east of the borough. We tried constantly to get answers about misconnections, central to the message we shared. It was impossible to get anyone from Haringey to come to the festival. There always seemed to be a lot of finger pointing & resignations if memory served. Theo Thomas was always great. Good to know the London Waterkeeper is going strong.
The beam engjne in Markfield park is run by a team of enthusiastic volunteers who open it for steam days several times a year.
Fantastic reporting! Thank you ☃️
I'm local to lordship rec and the sewage stink is really awful. Thanks for looking in to it. really vile
How can a homeowner discover if their property is misconnected?
Thames Water (in London at least) identifies properties that are misconnected, and writes to homeowners to let them know (then goes to councils if homeowners don’t fix it).
But it’s inevitably a hugely undiscovered problem — the process of finding misconnections is so long winded, and depends on volunteers literally wading through local waterways, like Ben from Clean Up the River Brent, who we spoke to for the article we did on this topic back in April or so. That’s why there’s such a mismatch between the reported numbers of misconnections and the much, much higher estimated real figures (eg Thames Water’s estimate that 1 in 10 properties in the area it covers are misconnected)
If you're feeling adventurous, you can tip some harmless food dye down your drains, and see if it turns up in your local river. Otherwise, depending on where you live, your gutters should go into a different drain from your kitchen sink etc. Unless you're in the centre of an old city.
A saying I remember from one of the displays at the Markfield Beam Engine is "Highgate's rain is Tottenham's pain" but this seems to be considerably worse...
Thank you to Rachel Rees for your info re. sewage system zones. We are in Tolworth (very outer suburb) which is in the catchment area of the Hogsmill River. Our house is in a development built around 1907 and I would dearly like to know if we have separate or combined sewers. We lived in a Philadelphia neighbourhood also built around 1907. Most houses had separate sewers but some had to be corrected. I led a campaign to unearth the relevant info. from many disparate government offices. Friends of the Monoshone was our name . We used water samples at each connection to identify the culprit(s), coloured a map of the whole area to demonstrate the stats' implications, and shamed the Water Dept who had failed to act on their own stats.
Here's another idea: dig rain gardens so far less rainwater gets into the pipes but goes straight into the aquifer.
One quick technical point: dissolved oxygen is vital to aquatic life. Nutrients from sewage reduce DO, using it as part of their decomposition, so polluted water is associated with low DO, not high. A significant pollution event will crash oxygen to zero, and everything in the river will die. We have seen this multiple times on the Brent. Healthy, moving water, with low pollution, and a plenty of plant life, will have high levels of dissolved oxygen.
Lewisham leading the way! Good to know, or Thames water haven't been investigating misconnections here