Report - - Fleet CSO and Storm Relief, London Dec 16 / Feb 18 | UK Draining Forum | 28DaysLater.co.uk

Report - Fleet CSO and Storm Relief, London Dec 16 / Feb 18


more tall than ginger tho.....
Regular User
River Fleet CSO

The River Fleet is the most famous underground river in London. It was certainly at the top of my list of things to do under the smoke. I am particularly grateful to both Adders and Ojay for their detailed accounts of it, which I’ve read through dozens of times now. Adders for the map, which got me off to a flying start at the end of 2016 and Ojays for the description and photo of a certain really useful lid (where Mrs Brown and dog Tiddles nearly ended up across the road!) which made completing this monster CSO actually achievable.

This report covers the whole lot of the main line Fleet Sewer and most of the Storm Relief, which runs much deeper than the CSO at the upstream end and regularly receives overflows from the main sewer above.

I’d take a seat if yer gonna read all of it. There’s lots to see down there and I didn’t hold back with my camera! I’ll describe my mooches from the upstream end of the CSO first and the Storm Relief last.

I’ve been down various parts of the system five times now from only two lids! I saw the upper most part on the fourth visit and dropped in at that really useful lid not far from the Regents Canal and walked upstream as far as I could before I started going downstream again! At that point I turned back and took pics.

Not sure which way it flows here but at the far end it joins with a fast flowing 4ft concrete egg falling away from the Fleet.

Turning around and these twisty tunnels soon drop into the Fleets main line

The tunnel on the left, I assume, is the River Fleet, which rises in Hampstead Heath. The tunnel right of the wall leads to where the previous two photos were taken from.

Or maybe this is the Fleet? Either way side pipes come thick and fast to begin with

There were several junctions like this, which seemed to alternated between the left and right pipes being bricked up. I didn’t venture far up any of them

And lovely curvy junctions

Londons “second staircase of DOOM” It really isn't that bad to traverse – I guess being tall helps. Keep mouth shut and hold onto the slimy handrail for all its worth. With gloves on of course! Check out the scour marks on the side, though, jeez….

There’s three or four almost identical chambers like this, each with their own drop shaft linking them to the storm relief below.

From Adders report :thumb

The development of the Regent's Canal area led to the section of river between Camden and King's Cross to be buried in the 1810's. By this point the entirety of the river downstream from Camden was underground, with the final earlier stages of the Fleet joining the subterranean in the 1870's after Bazalgette's interceptor sewer design had been implemented. The Fleet was now fully integrated into the London Main Drainage network.
The section under Regents Canal is pretty stoopy. Not too bad but bad enough! From this side (looking downstream) the floor drops about a foot 15m in, giving more headroom for another 15m. Then the roof drops 2ft to about 3ft high for the final 10m. Its not pleasant but a means to an end and all that. Keep mouth shut and camera strap shortened around neck! Maybe being tall isn’t so good….

This was a nice chamber to drop into. On my fifth and most recent visit with theVicar, the first thing we both saw was a discarded and drowned iphone in the overflow pipe. Somehow it hadn’t made it to the dropshaft on its own so theVicar helped it along its way. Best place for it, I say…..

Just downstream of this chamber was one of those loud but stoopy side pipes, that I couldn’t resist exploring at the end of my upstream visit. Well I’d been under for the best part of three hours already, so it’ll just be a piss in the interceptor in comparison. I’m rather glad I did too, after five minutes stoopin. At the top it seems to open up again to approx. 5’ but I didn’t fancy the inevitable soaking. Just taking this was bad enough!

Soon after we left the chamber that we entered from we could hear the roar of the Mid Level No.2 Interceptor, indeed you can easily hear it from the surface. The invert narrows along much of this stretch and the going is awkward, balancy, slippery and slow. As you pass the interceptor another slimy handrail is provided to give you something to grab onto if you slip while taking photos! The flow is quite fast here as the sewage tries to drag you down the interceptor. Hold on tight and don’t furkin slip! Presumably the interceptor is accessible here, or was, judging by the two tempting handrails that disappear down into it.

As usual its drier but shittier after an interceptor for a short while until more pipes add to the flow

The walk down to one of the newer sections took longer than we were expecting. The concrete pipes, chamber and overflow were constructed in the 80’s to accommodate the development of Kings Cross overhead. There’s an overflow on both sides, with the left one going under the main line to join the right one, which leads to another concrete pipe and drop shaft to the storm relief.

Unfortunately, this overflow has been bricked up. Fortunately, I knew there was another similar one further down, that wasn’t.

More bricked up side pipes, just like further upstream

Presumably this is a more modern tube line that couldn’t be kept out of the sewer. At least there was a sign to warn those who haven’t seen it ahead. Safety first an all that…..:rolleyes:

Cast iron reinforcement

This is one of the best overflow chambers I’ve ever seen; its mint! It’s a joy to look at and figure out its construction, which is impeccable as usual, except the odd leak! I couldn’t work out why the drop shaft is at the upstream end instead of the downstream end like all the others. The drop shaft connects with another side pipe but why didn’t they move the whole thing upstream 10m to accommodate that? Seems less efficient to me. It’s a long way until the next one, which presumably has something to do with its size. Unfortunately, these were the best two pics I got, despite help from the vicar, as I’d not charged me torch up the night before :(

You don’t see stemples like this in modern drains. That overhang looks far too dangerous and tiring on the arms

Finally we arrived at the Farringdon Road section, where the pipe nearly doubles in size. Much epicness awaits downstream of here, its probably the most feature packed two miles of drain I’ve walked down.

Normal flows disappear down the Mid Level Number 1 Interceptor, storm flows go over the weir, which has this shiny new handrail on it. The tag on it was dated April 2017. The Vicar and I left just down from here and went our separate ways home on public transport. I got a few funny looks I’m sure! Thanks for the good company again, mate!

Continued Below.....​


more tall than ginger tho.....
Regular User
This section was my introduction to London drains. I thought I’d pick a good place to start. I’ve done this section three times now and haven’t even started on any of the side pipes yet. First time was just before I met up with Mr Pink, when we saw in 2017 up on the O2, second was with a climbing mate, who’s never done a drain before (and probs never will again!), third time to check out the Storm Relief and outfall chambers as the tide had been in previously. I tell thee, going down this alone for the first time was an exploring experience I won’t forget. The lure of “just one more bend/ feature/ lid” is a powerful one.

Here’s the above photo taken from the downstream side of the weir, before the daft handrail was put in.

I quite liked this pic, taken just a bit further downstream

This one drops in steeply

Not far away is a nice, curved tumbling bay

Slippery concrete pipes passing underneath Crossrail, led to this brick invert-cum-concrete pipe. Or maybe the spraycrete had just washed away

These fibre-optic cables, came and went along most of the downstream section. It’s a pretty sensible idea running them through the sewers but led to an interesting conversation on a previous visit with the vicar about how the amount of porn going one way through the thousands of fibres must correspond with the end result going the other way ….. or something like that

The sewer splits here for 150m around an island, likely to be an underground toilet on Farringdon Road. Go left and on the left is an unassuming side pipe that leads to Pauls Pasta Steamer sewer (one day...) Go right and on the right there’s level access to the Storm Relief. Little bit disappointed with this pic but hey-ho, the brickwork's stunning

Half way along is a corridor accessible from either side, with a shaft, which leads up to a lid

The island looking upstream

Further along on the right, between the CSO and Storm Relief are these six arches and what could be large metal storage tanks or something partially visible beyond them, though not in this badly aimed pic!

Now the epicness and sheer scale of the lower Fleet becomes apparent. Holy shite, this horseshoe and them four flaps on two tiers are huge. On my first visit down here I didn’t know whether to stay and gawp at it or run all the way back to my lid! Talk about edgy – I was on full alert for any noises coming from upstream. The bloody tube trains rumbling away didn’t help with that! I could not imagine what it’d look like in here after its fucked it down with rain and there’s a spring tide.

Up the ladders on the left and this is from the upper level looking back upstream towards the Low Level No. 2 Interceptor, just behind the weir. There’s slimy hand and foot rails allowing you to traverse past it, which is easy enough, but as the flow’s quite strong here a slip would involve a terrifying slide to a final bar just before the interceptor that you’d definitely have to catch! The high tide comes over the weir and down the interceptor which prevents access to and from this area if you mis-time it. Of the three times I've been down this end I only had enough time to briefly look round it once. Check the tides first to avoid disappointment or possible benightment with rats (I've not tried the available lids from underneath!)

Turning around and this is the upper left passage that channels serious storm flows to the flaps at the end but there’s more to see beyond them.....

Check out these bad boys! The flaps from the other side….

Below the walkway^^^ is the outfall chamber to the Thames. As I was taking this the tide had risen to the concrete platform I was standing on. Time to go I think but I want to return here one day to have a better look around (and to take some better pics!). The two arched holes on the right are the outfall pipes of the Storm Relief, which I shall describe below and the two low tunnels ahead outfall into the Thames beneath Blackfriars Bridge

River Fleet Storm Relief

The Storm Relief, built in 1870’s, was the first drain in London that I saw, just hours before I found a lid to the Farringdon Road section. I still didn’t know what the lids looked like I just happened to park right next to one, that looked different from other utilities. I lifted it, saw brick spiral stairs so went down and down and then down some more. WTF am I letting myself in for here! I got to the bottom, looked left, then right, saw nothing so I sprinted back up, past loads of needles a good three or four full spirals up (WTF again!) and back out.

I returned a few weeks later, when I realised it was “only” the Storm Relief. It’s definitely not as feature packed as the CSO but there were a few things I wanted to see and thought maybe there was access to the upstream end of the CSO at a drop shaft, which would save me looking for more lids. Alas, I didn’t find one.

I walked upstream from my lid near Kings Cross for a while, saw nothing of interest after five minutes so walked back. After what felt like hours of not much, except a few twists and turns I came to this junction. I walked back upstream on the pipe on the right to see where it went.

It led to this drop shaft from the CSO, which I’ve just discovered was my favourite four arched one, and tumbling bay. I went up and continued along a short distance, when I heard a loud noise of rushing water, downstream of me thank fuck! Having read previous reports of this I’d been expecting it to happen somewhere I just couldn’t remember where! It stopped as I was walking back down to investigate and although the flow had obviously not been as bad as it sounded it but freaked me out enough to not bother with what was further upstream. I wanted to get as far downstream of it as possible before it happened again and my legs were beginning to tire

Below another drop shaft from the CSO. Can’t remember where I saw it though.

Walking downstream the level access to the CSO at the split appears on the left.

Soon after this, on the left (so between the Storm Relief and CSO) there were two smaller pipes, a lot of modern metalwork and two heavy flaps that I tried in vain to access. Maybe they lead to what might be the storage tanks behind the six out of reach, arched openings described earlier.

The Low Level No. 2 junction and dam boards, which prevents the Thames going down the interceptor at high tide, or used to…..

….as on another visit the dam boards had been removed or become dislodged.

Bubbles in the interceptor!

The Storm Relief splits in two, goes through two heavy flaps and ends up in the big outfall chamber, where it joins up with the CSO. I’ve not been able to get a proper look at these from the other side yet as the tide was on its way in when I was there last.

I did have a little time, though, to have a look round the maze of tunnels where there’s various penstock controls, some very much in use, others now defunct. There’s ladders going up and down to access viewing platforms on different levels and manhole shafts, allowing Thames Water to inspect their property at high or low tide. I’ve since leant you can access the Low Level No.1 from these as well. I’m not gonna lie, as time was running out and I was on my own I ended up just shooting stuff hoping I’d figure it out later. Well, some of it I can, some I can’t, so I’ll just leave these few here. I deffo need to return to this end of the Fleet to figure it all out properly for myself.

Feel free to correct me on anything I may have misunderstood or got wrong! I did the Farringdon Road and Storm Relief nearly a year ago now and my memory isn’t great.

Thanks for looking (and well done if yer read all of it!)​


feeling drained?
Regular User
Awesome work @tallginge and really nicely written words to go with the pics, as usual.

‘Hold tight and don’t furkin slip!’​

Good advice, as always ;-)

[edit] yep I posted my comment before part two too. Part two even better, you tell it well mate! Thanks for posting! Been looking forward to reading the full report and it doesn’t disappoint.
Last edited:


Staff member
Oops, I was a bit hasty posting and split the thread in two, try again eh :rolleyes:

Anyway what a load of shit!

Great seeing that lot again, good effort mate because some of it, especially the upstream stuff is a right pain to traverse in places, I must have missed it but you forgot to mention that bent double stoop up a twin split with face being splashed with fresh!, must have been hell being a lanky sod :p

EDIT: Oh wait, you did (the Regents Canal)... GRIM! :eek: :D

Cracking pics and another good account of one of the big 3, now you just need to finish the Westie/Ranelagh off, but be careful some real sketch bits with that lot, (again upstream) ;)

11/10 :thumb


more tall than ginger tho.....
Regular User
Thanks lads yeah I try and give out good advice occasionally and yeah yer wouldn't want to furkin slip, which is very possible passing that interceptor, more so than anywhere else along the fleet.

No worries Ojay, yeah I bent double under the Regents Canal alright, giving the fresh a good whiff as i went! Yup I've started 'em we've just gotta finish 'em now. I've come across several of them automatic flaps that I daren't pass on my own, especially when there's less usable lids available in some areas. Also well aware that I've not come across any noxious gases yet that could prevent me retracing my steps. One to watch out for and make an educated judgement on (with a 4 gas of course!)


living in a cold world
Regular User
Cracking work mate! This place sure takes some perseverance and you've nailed it. That metal railing at the mid level is an interesting surprise!


more tall than ginger tho.....
Regular User
Thanks bud, yeah that's what we thought! Wondered why they put a railing on both sides though. Its not as if you'd fall far or into anything dangerous on the left. Sewer tours maybe or just health 'n' safety more likely. The hoops that lot have to jump through....I suppose its a good thing if you're working


Staff member
Thanks bud, yeah that's what we thought! Wondered why they put a railing on both sides though. Its not as if you'd fall far or into anything dangerous on the left. Sewer tours maybe or just health 'n' safety more likely. The hoops that lot have to jump through....I suppose its a good thing if you're working
It's odd for sure, the other interceptor tour is an accident waiting to happen :D



I Go Where The Drains Are
Regular User
Great job doing the entire thing.
One thing that used to trip me out was the difference between being in there at 3am vs 3pm.
At 3am it runs almost dry and clear... At 3pm you nearly get washed off your feet.
BTW, the Fleet Storm Relief is the most boring tunnel in London, good to get done and out of the way.

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