Rat, liner, drain, extension, pest, council, Thames, London, mouse,

Dear UK

I’m a homeowner living in South West London.  

I plan to put this message up on every forum I can find that has anything to do with rat infestation with the sole intent of helping those who have homes that have been ravaged by rats.  No one should have to jump through the millions of hoops I had to go through in this country to fight vermin.

We live in SW London and moved into our home back in 2013.  By all rights it looked amazing when we got it and everything from a full building survey point of view checked out.  The house had a ground floor extension built in 1987 and all the regs documents checked out to.  This extension was built over the top of a sewer that served four houses including mine which these days is the sole responsibility of the water board.  Thames in our case.

The first time I became aware of rats was when I could hear some really loud scratching/banging come from under the kitchen counter.  Very concerning to say the least when you have never experienced anything like that.  I did not initially identify it was a rodent and thought at first it was a plumbing issue from the type of banging.  To add to the issue we had some kitchen lighting under the cabinets which did not work at first.  The sparky showed me the cables he pulled out from under the cabinets and you could clearly see the cables had been chewed to bits and this had happened some time ago.  Certainly before we moved in.  Clearly, though, the many people who would have lived here prior to us were quite happy to live with rats in their kitchen.

In the beginning this was an extremely stressful situation because we lived in fear of these things as this type of evidence suggested the rat was coming up from under the sub-floor to the main floor in the kitchen where we eat.  These creatures are sewer rats and carry untold diseases that are fatal to humans.  So here is what I did on the long road to recovery.

Initially, I invested in some traps and rentokill grain bait and put them right next to the area where I could hear them under the kitchen cabinet.  Sure enough it was not long before we could hear the screams of rats in the night.  It was not a pleasure to start my working day by removing the dead rats from under my kitchen counter.  It was starting to become a regular thing.  I would catch a number for a while and the problem would go for a few weeks then it starts all over again.  In the end I bought three massive cans of expanding foam and emptied the lot down a small square opening that sat between the main floor and subfloor.  Really painful shifting a large fridge to do this. Rats never got back through that hole anymore.  What we found after this was that we were routinely plagued by flies.  These rats were dying from eating the poison and rotting under the house.  It constantly stunk like a farm in our living room/kitchen as it’s all open plan.  The smell of their urine did not help either.  These creatures are totally incontinent.  I knew they were pissing all over the kitchen floor and daily scrubbing involved to eventually get rid of it.

Anyway once I did the foam I thought that was the end of the nightmare but this was far from it.  Sure enough we started hearing noises from under our living room floor and mostly near the party wall side.  Thankfully our house has no carpets and just varnished floor boards.  This made it dead easy to lift up a board.  When I did this the smell was horrendous under there.  Loads of rat droppings and this was the air we’re breathing in.  I had to go around with decorator’s filler around all the skirting boards to stop the flies from escaping which equally can carry disease.  Really great lugging heavy furniture around several times to do this.  How many weeks did we spend chasing flies in our living room with fly spray!  

I had to invest in two foscam cameras which I mounted to the underside of the floor board that monitored the area of traps otherwise I never had a clear idea if anything was dead until flies appeared. My daily routine always involved checking the video logs for rat movement.  No surprises that the solution worked and could see the vermin checking the ring of death I made for them.

It was then that at this point I could see we have a major rat problem that no amount of traps or bait are ever going to fix this.  I was totally lost as to where these sods were getting in.  Was it from the neighbour’s house? Were they digging under the decking next to the back of the house? Were they getting in on the side of the extension next to the neighbour’s extension?  A side of which is so narrow no access is possible?  No idea at the time.

I did the next thing and tried a few pest control companies after seeing examples on TV of others with rat issues.  Wow, is this country full of useless pest controllers.  These guys just turn up and say “I’ll put bait down” and charge you more than what you can get it for from a shop online. I thought they might try and smoke bomb the subfloors through the access hatch to the sub-floor but no.  I suggested the idea and they looked at me like I was crazy. “Dah, what’s a smoke machine?” I’d seen this example on TV from a decent pest control.  There are none in my view where we live.  

I started doing my research and discovered on the net there are loads of cases like this as a result of past building work.  I was starting to build a picture in my head and it made sense these sods are sewer rats.  They’re not coming from the garden or anything above ground.  God knows I tried to look at every inch around my property to rule that out.  

I ordered a basic drain survey from a so called drainage specialist off checkatrade and we had a look together. Sure enough we saw two abandoned pipes.  One which used to carry the the previous toilet waste exit.  The other closer to the present manhole at the side of the extension which was a former guttering pipe exit.  I knew when comparing the other houses with no ground floor extension.  The 80’s builders had not bothered to seal off the old pipes.  It’s amazing how they got away with this but I am sure they get away with shortcuts all the time.  The drain guy suggested installing a metal rat flap.  A Vermead I think from memory.  That model costs an eye watering £300-£400!

In my research I discovered that some people had installed rat flaps in the manhole of the sewer like the one he suggested.  Now a few points on this.  They are not 100% effective.  There are two types on the market.  One is the plastic type which is blue and red in colour and has a flap secured by a spring.  The pest control calls these rat flaps but they’re actually called non-return valves used by water companies.  These are total rubbish.  The rat can chew these, although that never happened in my case.  Any mass that gets logged between the flap and floor leaves it open so the rat can just slip by and it happened in my case.  After a year the spring gave up.  It gets choked up with paper and wipes and the door will not fully shut tight anymore and the rat just lifts up the flap with their noses.  Sure enough the rats were in the old pipe work again and up in the sub-floor.  So that was £80 down the drain, as they say.  

I was totally frustrated by this stage and so I thought I will make this a Thames water issue.  When I first called Thames I got through to a lady whose attitude was ‘why on earth are you calling us about this’?  I was persistent. I described the problem and they sent out Thames operations, a young bloke in a small van trying to convince you that it’s not Thame’s problem.  Their system is loaded with rats which he denied at first but eventually I got it out of him.  I spent a good hour pushing this guy to take action and had to show him pictures of dead rats I had killed from under the house.  To add one of the photos near the toilet feed exit even had a dead rat in the picture.  This guy just sort of looked at the photo squinting to see it scratching his head.  Amazing!  Is that a rat?  

So after seeing the evidence he had a look at the visible man holes in the neighbour’s garden. My neighbour at the start of the row of 4 had a rotten manhole.  The guy had just been covering it with timber.  It must have stunk in the summer and it’s right next to his patio door.  Amazing! Anyway this kind of thing provides excellent access for a rat to go up and down.  Thames replaced his cover free charge a few weeks later.  A few more weeks went by and there were more rats under the house.  I called Thames again and they sent out the same bloke.  This guy had the same attitude and showed up at my front door saying ‘What do want me to do about it’?  He started saying you have a rat flap facing the public sewer.  The other end of the pipe to you has no sewer access.  I did not believe it and insisted he do more.  

So what he did was send out Lanes Plc, who did a full end to end CCTV survey and they also put bait in the manhole next to my extension.  Lanes said there are no rats in the pipework running over the four houses to the start of the access chamber at the opposite end to me.  However they did not tell me one thing.  At a random occurrence I called out Sutton water early on that week as I had a contract with them and explained the rodent issue.  On a random chance Sutton turned up at the same time with Lanes. Great! Now the Lanes group whispered in the ear of the Sutton water man and said “his issue they have just cut the pipes and that’s why he’s getting rats.” Lanes however did not tell me that!  They just jumped in the van and drove off.

More weeks went by and more rats appeared again. Now, I had sat back down started researching the web for any kind of case study to assist.  The primary suggestion I had come back was to excavate down.  However one cannot do this for a few reasons.  It would make your home uninhabitable drilling down throw that much concrete.  You’ll also have an exposed sewer in your house. Also if I had started drilling down I risked a cave in on the sewer the floor is built on top.  

I decided at this stage to try the legal route to fight this.  I was going to escalate this with the council and contact a lawyer to see how to make Thames liable to deal with the issue.  I figured the rats are coming from the sewer and Thames own the sewer.  Let’s start with the council.

I called them and explained the situation on where and how rats are getting into my property.  I explained there is an act which requires homeowners to keep their homes in sufficient condition as to not cause a public health hazard to others.  I forget the name now but it exists.  I thought I am going to keep badgering the council indicating what a problem Thames’s sewers are for me. They would only send one visit out which was another useless pest controller from Sutton Council.  I told him where they’re getting in and he just scratched his head.  His advice was to pour cement down into the sewer and then plead total ignorance when Thames get a call from my neighbours saying their sewer does not work when the toilet doesn’t flush away.  This a waste of time! Next, I was talking to the lawyer trying to go for Thames under the water act.  Totally bulletproof.

Meanwhile, I ended up upgrading to a marine steel rat flap which can cost up to £400.  These things have dual flaps mounted inside a casing as so not prone as to getting wedged open but again not 100% effective.  They do have serrated sharp edge on the flaps which is great for catching tampons.  Really pleasant to look at. Objects like this can leave the flap open and the rat will get by.  Even under normal conditions a small baby rat can get past as the flaps cannot sit fully flush on the floor of the sewer pipe.  That’s why they are never 100% effective.  I had mine installed 9 months from having no issues until one day I heard the sound of screaming under the living room floor.  I had caught the biggest rat I had ever seen.  This sod had gotten past the flap and clearly had been living on all the food waste from the sinks the houses feed into. So the flap had been open by an obstruction I think. Before you think what about the other end of the sewer, well, the start of the pipe has no access to the public sewer.  It’s just a brick chamber.  So one way in and one way out.

So the final option I had discovered was to go through drain lining.  Basically, this is a pipe within a pipe. Now this was not going to be straightforward.  First, you need to find a reputable tradesmen to do this.  They screw this up and anything above the sewer and that being my kitchen in this case is getting dug up. I contacted several of these guys.  Some of them would not touch it.  Some of them were ready and willing to go at short notice after a quote is issued.  However, only one of them pointed out something I did not know.  If you’re going to be lining a sewer shared by two or more houses you need permission. None of the other so called drain lining firms pointed this little fact out.  Anyway, I got a price and plan for that.

The next issue I has was that I had to get the toilet waste re-routed.  After all I am going to seal up the redundant toilet waste hole the new one runs parallel to.  Got a few quotes from general builders and also approached Sutton water for a quote.  I went with Sutton water.  Less likely to disappear into the night like many rogues out there.  Plus the surveyor clearly understood the issue better then the general builders. The re-routing was going to be gamble for the toilet waste as I was going from an internal route to an external one.  So the new pipe would run inside the house across the kitchen ceiling, core drill through the wall, and down into the sewer on the other side.  The boys did something else.  Instead they re-routed the pipe to go across the extension roof and then down.  Now this I wanted to avoid as the gradient is not 80:1.  I did not know they were doing this until I saw it towards the end of the day.  The other issue was that they had to open up a box on the extension roof that hid the present pipework to take it out.  I again had no idea they would have to open this up.  They had to in order to get the legacy pipework out and I had no warning this was coming.  Great!   I had to get my roofing contractor out as I had an EPDM roof and the box was covered in the rubber material.  Thankfully he was able to come out at a day’s notice and work on the box with Sutton at the same time.  Very stressful as I had no guarantee of getting the roofer out and Sutton had already started ripping into the house so it was part done.  Anyway, they sorted the new roof box, and got the piping in and working.  No pipe blocks from the new work!

Sutton installed new boxing in the kitchen where they had to break open the ceiling to get to the old pipework.  So this meant having to get a plasterer out to plaster the new box in and paint.  No big deal but had to get 3 quotes which varied massively.  

Last step now and the most nerve wracking was the drain lining.  So first step was to get approval from developer services at Thames water.  Now keep it short and sweet with this lot.  Send them a mail describing what you need to do in minimal terms.  You will have to ring up and chase approval.  In my case they were okay to approve.  A few of the decent drain specialists advised Thames can be really difficult about this but they were okay in my case.  Got the approval mail and ready to send to lining contractor.  I got the lining firm out and they did a survey before touching anything.  You can have a patch or lining.  In my case it was lining given the size.  These guys from UKDN were pros and work with Lanes part of Thames group.  I explained the issue to the two chaps working on it and they got the picture.  Within 2 mins of putting their cam down they could see the issue faster than any of the others.  A redundant gutter pipe feed just near the mouth of the manhole and of course the old toilet waste exit.  I spoke to them for a while afterwards and they said it is a very common issue with extensions.  Builders are supposed to feel old pipe exits with glass and cement to stop rats.  They rarely do! This was true as I had read many similar horror stories on the net from people having these extensions been built over the sewers.


So now you have read the long story.  Here is the short version of steps to go through:

  1. Buy foscam indoor cameras and attach to under your floor board.  Do not leave on floor where rats walk.  They will eat the cam or the power lead to the cam.  
  2. Buy lots of rat traps. Coat the things in peanut butter.  Buy the pest control bait.  The grain is total rubbish.  
  3. Contact the water board and report the issue.  Fight to the point where you’re getting threatening with the engineer in order to get them to do a visual on all of your neighbours manholes that share your sewer.  If there are no issue in the neighbour’s garden demand they do a CCTV survey.  Be prepared they will deny everything.
  4. Get your own CCTV scan of the sewer you are using and get evidence.  Thames will not believe your own footage, as I found.
  5. Make plans to re-route any pipes using the shared sewer to another location in front of the open pipework.  If you are mid-terraced you are basically screwed.  You have to side wall to reroute anything.  End of terrace, no problem.
  6. Write to developer services and get permission to install a drain liner and rat flap.
  7. Buy a vermead rat flap.
  8. Contact drain lining firm to install the liner.

List of contractors I recommend in London to help:

UKDN – Did my Drain lining

Drain scan in Morden.  Robert provides amazing advice.

Sutton Water – Pipe work. Did my new toilet waste.

TSS roofing – for any roofing needs.

M&M decorating Morden.  Chap called Marcin.

UPDATE: 21/11/16

Adding an update on other avenues on trying to hunt down paths that runs can use to enter a home.

  1. Checking drains from inside to the outside of the home.  Your own private drains could be a problem leading to infestation. One method to check this would be to use a waterproof camera with a cable run of say 30m or more.  These can be slid down the toilet/sink/basin waste pipes to eventually see the camera head come out into the sewer.  This website http://www.scanprobe.com/hire-drain-cameras.html has a number of options but I think the one that is in a case with an 8″ screen would do the job.
  2. Drain lining example.  Not everyone may understand how these are done so including an example here.  Renoline seems fairly common in the UK but drain lining is done internationally and there are hundreds of youtube examples.  https://www.youtube.com/watch?v=9BLTrkJDx58 and https://www.youtube.com/watch?v=K80FmLHnPEk
  3. Air brick covers.  Rats and mice can chew there way through an air brick.  Example of products here help to defend against this.  http://www.pestfix.co.uk/Mouse-Mesh-Air-Brick-Covers.asp?gclid=Cj0KEQiA08rBBRDUn4qproqwzYMBEiQAqpzns9L2k7UjJW341cCJAk4Kd9z-FRM1I5KC9ADbp-zS9_MaAlNY8P8HAQ

20 thoughts on “Rat, liner, drain, extension, pest, council, Thames, London, mouse,”

  1. Thank you for posting this, although it fills me with fear. We are just a the point where Thames water are coming out and we are having a metal rat flap fitted.


  2. I have so much sympathy with you regarding the sewer rat problem….we have had a similar problem for over 35 years and everytime I think it is resolved they come back. We have had 2 drain surveys and a metal rat flap fitted and things have been quiet for 18 months. We have also had a new extension ceiling and the whole house rewired because they ate through a wire and as you have stated the insurance company do not want to know .But to my horror they are back. We have contacted the last pest controller we used and waiting for his response – but think drain liners may be the only way forward. We are quite local to Sutton and it would be most helpful if we were able to speak? Are we able to do communicate outside of this forum – I am now desperate for help and finding that the rats invade my thoughts throughout the day and night?


  3. This is literally like reading through my life for the last year – losing the will to live and totally impressed by your perseverance. I haven’t investigated nearly as much as you have, but I’ve just found out that our insurance WILL cover “removal” of the rats and I’m determined to get my money’s worth from them. Can I just confirm that your sewer runs under your kitchen? How on earth did they fit the rat flap if it’s under the kitchen? Would appreciate a personal email too if you have time.


    1. Hi Georgia,

      Thank you for your comments…

      I understand your frustration and you have my sympathy’s when dealing with the saga it is.

      Yes, your correct the sewer (shared public sewer) does run under kitchen/extension. the sewer is around 1.5 meters below the extension floor.

      To answer your question on how the flap was fitted there is a man hole hatch on the side of wall/extension. Open the cover and slide the rat flap into position. It may not fit at first as old clay sewers like mine are not a perfect circle. The flaps allow some bend but not much. I had to get a builder to widen the aperture.

      Two points to about the rat flaps I want to note:
      1. There 99% effective. There is a minor risk that baby rat which is no wider than a 5p coin could slide around the edges of the serrated blade flap. They get in and grow and then breed. This happened to me.
      2. Your only ever blocking one end of a pipe. If the rodent is traveling from the opposite side they still get access.

      If you click contact on this blog it has my email.



  4. Hi

    This is also like reading through our story for the past two years. We have them in the loft space above our kitchen /dining room extension). They’re coming up through the cavities, via the drains. We think. I think we have gone through all the stages noted here (though fitting non return valves, not the tampon chomping ones). Anglian Water has even lined a segment of a drain. Pest control put in mesh and foam
    and what not (which is least they could do for the £1k we paid in total). It was quiet for a couple of months. I dared to hope we could live in peace. We even paid for fumigation and rewiring (though I can still smell the urine/corpses/droppings some days dependent upon the weather – a factor, i’m sure you’ll know). For about a month afterwards I felt completely exhausted and drained from battling with the council and water board and living with the stench oh it. I was just about recovering and now, this evening, we’ve heard the tell tale scratching and banging. This time I really do not know where to turn. There must be something structurally seriously amiss. It just feels like we’re an open target. You all sound so calm about your situations which is admirable because it’s completely ruining our lives. I just feel so dirty living with this.


    1. Hi “At_wits_end”

      I’m sorry you also are having such a horrific time. Your story is near identical to Marion’s above I spoke with.

      Trust me when I say I have been very stressed by it too and know exactly how you feel. I’ve never fully recovered from it and I am still not holding my breath.

      You did well to get Anglian water to make repairs. That’s a lot more than our water board did.

      The NRV’s are okay for a while but eventually the spring’s wear out and the flap does not fully close. Plus if there is any obstruction on the lid (typically from tissue or wet wipe build up) they will take the opportunity to lift the lid with their nose. Plus since there made of plastic they get chewed.

      I’m planning on making an update hear about tactics to track how these furry pests get in. I think everyone’s approach is to look at the problem from looking at the outside of the property and checking the path back in. That’s fine, but the other approach is to look at the issue from inside out. Remember every property has a route from their toilet/sink/basin etc to the outside drain. Few of us every check these routes. I’m going to post some idea’s for kit to explore for holes in this method.

      Going forwards my latest advise is never buy a property with an extension on the ground floor. Especially if there built over sewers. There are too many builders out there who fail to cap off/isolate old drains to the sewer making a perfect route for rats. These guys are supposed to feel all the old paths with a glass/cement mix but typically don’t always bother leaving the home owner with a nasty problem of rats.


  5. I have a similar problem and getting nowhere in finding a solution. I have a few questions -Were the uncapped abandoned pipes under the extension and still joining the existing drainage system, such that they were not visible from the new inspection chambers? Were the rats in the new drains but accessing your property through these redundant pipes and into the property through the cavity walls? I have a concrete floor in my extension and I’d have thought this would have blocked off any unused pipe ends at ground level.
    I’ve had the drains inspected on two occasions and fitted rat flaps but with no success. The problem started some 20 years after the extension. It’s all very confusing. Any help will be appreciated.


    1. Hi Sheila,

      Sorry to hear your also experiencing this awful problem. To answer your questions:

      Were the uncapped abandoned pipes under the extension and still joining the existing drainage system, such that they were not visible from the new inspection chambers? Yes, this is correct. The only way to see the unused pipes running into the shared sewer was via the man hole to the side of the extension with a drain camera. You cannot see this with the naked eye.

      Were the rats in the new drains but accessing your property through these redundant pipes and into the property through the cavity walls? No. They never got in the cavity walls but accessed the sub-floor of the home through a redundant gutter pipe. I have a 1930’s home and they were built with floating floors so there is a 30cm void between the foundation floor and the living room floor they used to walk around in under our feet per say. Prior to the extension there was a gutter pipe that ran down into the shared sewer. The builder did not cap off the run from the sewer to the gully where the gutter pipe would have deposited water from the roof.

      I have a concrete floor in my extension and I’d have thought this would have blocked off any unused pipe ends at ground level. No do not assume this. Any pipework that was on the back of the house and drained into a sewer would have been built over not removed. There supposed to feel old pipes with a mix of glass and cement but in the countless reports I have read all over the UK in my dealing with this they do not bother. My extension floor is by appearance built on concrete too however since I have the freedom of been able to access the sub floor I can see the extension was not one solid block of concrete from the foundation to the foot level. It is in fact floating and i can see the air bricks between the extension floor and the living room subfloor where the two floors meet. The rat used to travel through the air brick to the rest of the sub-floor with no restriction.

      I would get UKDN in per my link. I had all sorts of inspections by so called experts who missed the unused gutter run until these guys and found the problem within a few mins. Pest control in this country who often offer this is a bad joke and there are many plumber firms who do camera surveys on the side to make a bit extra. Don’t waste your time or money like I did. Only every get large firms that do drain work only.

      I don’t what age your house to understand how the foundations are built but would be good to know if you have floating floors. If you have vents all around the bottom of the house that’s usually a 30’s home.

      If they are in the cavities of your home then they have dug there way in from the sewer through a dead pipe or broken pipe. Often if you cannot find any holes or pipe breaks from the sewer then look for the problem from the inside the home out to the sewer. I have uploaded information about getting cams that you can run through the toilet/kitchen/bath/sink waste pipes to where they eventually come out into a sewer, french drain, or septic tank etc…

      Hope this helps and please let the world know how your fighting this.



      1. Many thanks for getting back to me.
        I also have suspended floors in the original part of the property. The rats have taken poison from there. They are also in the ceiling spaces and attic. so I am assuming they are climbing up the cavity to get there. Luckily , touch wood, they have not found their way in to any rooms. There’s no evidence of them nesting in the attic and the other areas are not accessible to check. Also, there’s no evidence of them outside the property, so must be getting in through some unused pipes. I’ll contact UKDN and also check your link for cams that can run the inside to ouside.
        Thanks for you help.


  6. Thank you for posting this article – it has really helped me out! I am at the stage where I have found (a very suspect) disused drain pipe and want to undertake drain lining to block it off. However I believe it sits on a lateral drain (my neighbours drains connect and then this pipe runs over our boundary, but my drains that are in use connect after this one) and my understanding is this belongs to Thames Water. I would greatly appreciate it if you could share the note you sent to their development department – I want to make sure I am saying the right things so they will understand and agree – thanks!


    1. Hi LJ,

      I’m glad the article has given some guidance. Please be careful who use to do it. There are loads of people doing this who just have the machine and making money from it who have no idea what there doing.

      Here is the email I sent them:

      Hi DS,

      I have requirement to install a sleeve into my sewer. The specification is Renoline super liner 100 or 150mm liner, to fit pipe. Using polyester resin system.

      If you have any further questions please let me know.



  7. Hi, thanks for this art, I am suffering the same thing, after using a bore scope in my walls etc I think I have found the source, and it looks to be consistent bodgeing of the drain when the extension was built and then various people over the years moving the downstairs toilet around. I have someone coming round to CCTV the drains and I hope they are able to do something like you so as I don’t have to break the concrete subfloor, nor have to tear half my house down to sort it.

    My question however is, why the renoline super liner?


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