Image of a boy feeding rats in a drain
When we get the call for a job involving any internal problem with rats, we start by conducting an extensive survey of the property which includes any adjoining parts of the ‘structure’ when it comes to rats you have to see the whole picture, so we include any properties attached to the one which we’ve been called out to. Rats are without doubt the biggest pest in numbers that we deal with, and we carry out more rat control in Maidenhead than anything else and that includes all the insect pests we deal with. 

Rats and drains - how we control rats in Reading 

When it comes to the rat treatment, we look for the glaringly obvious things like a bad joint where the mortar has slipped out, or a gnawed open air brick and the ubiquitous pipe hole that was left over from when the new kitchen was installed. But there is one fact that we can’t escape when looking at rat problems and this is that about 70% of internal rat infestations stem from a fault under the house in the main drainage. Throwing rat poison at the problem in a situation like this just isn’t the solution, you need to strip the layers back and understand the narrative and the only way to do that is to look inside the drains. 
So what lies beneath your home? 

Types of drains 

There are two different types of drainage system: one that connects your house and every other house in the street to the main, water companies sewer in the street outside, and the other one which only serves one property at a time and is a series of tanks that settle the solid waste from the liquid (99.9% of domestic sewerage is just water) and allow to drain away into the surrounding ground – these are termed cesspits or septic tanks and usually found on rural properties. 
The first system mentioned commonly has rats running around inside; they don’t actually live inside these drains as the pipes are quite narrow and there are few dry areas for them to nest in, but they do act as an easy route for rats to move around the streets of our towns and cities undetected. On the plus side for rats, as well as easy movement, these drains are full of food, and they have plenty of water. Combined with that, the ambient temperature in the drains, is about 5 degrees higher than the temperature outside, so handy in the winter. 
It’s generally the drainage system that connects up to the main sewers where we find the most problems due to the scale of the system and the sheer amount of defects that occur along its length; rats ill not live in these drains but faults and open manholes allow them to slip inside and from there, they will explore the system and if there are faults near, or underneath your property, then the chances are you will have a rat problem inside your home and I’ll explain why in this blog. 
Picture of a rat coming to investigate the noise and light from the camera head 
A rat living inside a drain
Redundant section of pipe - nice and dry and somewhere for rats to curl up and sleep 
rats nest inside a drain

The super skills of rats 

Let’s just establish that rats have three major skill sets that make them our Number 1 pest: 
Firstly, they are intelligent animals, and we underestimate them at our peril; we’ll see rats enter via the drains at one house in a series of link detached properties (these are the houses that although they are detached from one another, they all have a garage linking them between), in this case we saw rats come in and travel through the first garage, through the next house and next garage into our customers house. Put a rat in a maze and it’ll figure out the route through and remember it in no time at all. 
Secondly, they are resourceful scavengers and rats will look into every crack and cranny seeking an opportunity, we often see brickwork of drain inspection pits in older properties where rats have gotten into a building through years and years of gnawing away at an edge on the exposed bricks and squeezing through the gap created. 
On the note of squeezing, the third super skill goes to the fact that rats can slip through the space of a modern fifty pence piece; in today’s modern construction and the speed in which houses get built do you really think that gaps of that size aren’t noticed? We’ll see a wide range of building defects that you wouldn’t even look twice at, which have let rats into a building. 
Rats are determined, clever and highly capable so when rats are in the drainage system outside your home, it’s a given that they are working on getting inside. 

Rats and drains = the perfect combination 

Having taken into account the super skills of rats, when the drains connect up to the house any defect is going to be exploited by these animals and you will find yourself with rats in the loft and rats in the cavity walls and we’ll explain why that is. 
If you’re drains enter the building to connect to something like a toilet through the outside wall, in effect they punch through underground and you have a point of access into the cavity wall as it passes through, this leads up and into the loft. The easy way to find this out is look for a hollow vertical box somewhere in the kitchen or utility room if you have one, alternatively look at the roof and see if a pipe protrudes through the tiles – this is the stack pipe or soil vent pipe that connects the house to the outside drain. 
The common problems we see with drains are as follows: 

Faults within the drain inspection pit 

Drains should be fitted with an inspection pit outside of the property where the separate lateral drains of the buildings’ system come together; some houses have a single stack pipe where the kitchen, bathroom and toilet all connect before leaving the structure. Others have multiple stack pipes because the layout of the drains is spread over a wider area and usually these all congregate to a single point before running off to the sewer. 
Either way, you should have a pit that ideally sits outside of the building’s boundary; we do find that many rear aspect extensions are built over the top of these pits because the builder either wanted an easier job or just didn’t understand what he was doing. Unfortunately, this is far too common an occurrence and creates major issues for homeowners when things go wrong as there is no access into the inspection pit. 
Faults in inspection pits are the most likely scenario when the issue lies with a drain defect, these can range from precast concrete sections of the pit walls sinking, leaving a gap between the topmost ring and the cast concrete lid enclosure. In this case, rats will simply climb up the inner face of the pit, over the top and then follow the line of pipework into the property. 
Other faults can appear in older pits where brickwork has either crumbled away or the mortar joints has been worked at by generations of rats, they gnaw away at the bricks until there is a space big enough to squeeze through and into the void on the other side. Modern inspection pits are simple plastic constructions, and these will be attacked by rats; all modern drainage is plastic and the sharp teeth of rats make short work of getting inside. 
Older pits will sometimes have a vent pipe that connects the pit to the outside and you can see a cast iron snorkel that sits just above ground. These are typically found in older, period properties when the owners didn’t need to make provision for cars; as the properties have been modernised and driveways put in, these snorkels have been taken out. If the opening on the side of the pit hasn’t been sealed, rats will dig their way out from the drain and we can find them climbing into vehicle engine bays and causing damage. 
Finally, the most common fault is where alterations have been done to a house, one or more of the laterally running drains has been taken out of use and then incorrectly capped. We see plastic rubbish bags, rubble, expanding foam and even just open ends terminating under floorboards in houses all of the time – this is not the correct way to seal a drain and will undoubtedly lead to issues in time. 
Rats have worked at these bricks for generations to finally break through 
Gnawed bricks
Builders can be heavy handed and not fully understanding drains 
Simple drain fault
Old snorkel vents; these are often broken off and a route out for rats 
Snorkel vent

Faults in the service vent pipe 

When you look at the waste system of a house think of a tree; the vertical trunk is the soil vent pipe or stack pipe as its often called, and this runs either through the roof to vent into open air or inside where a one way air admittance valve or durgo as its called, sits at the top. When you flush a toilet, gravity works on the mass of water and waste to allow this to drop down the pipe, without someway to equalise the pressure this mass would stick and refuse to move.  
Rats are capable of climbing the inside of a stack pipe and it doesn’t matter whether its plastic or cast iron, do not underestimate the ability of rats to climb as we’ve had rats in toilet pans on the second floor of a house fitted with modern plastic pipe. 
Faults occur in the stack starting at the bottom with the resting bend; this is a curved part of the system that sits at the junction between the horizontal pipework and the vertical. The ground that your home sits on is moving, sometimes gradually over years and at other times quite quickly and this piece of pipe is under strain due to the downward force applied to the immovable horizontal object. We see a lot of faults in clay pipes as although strong in compression, tension forces shatter the pipe, and this is where rats will now escape from the sewers, burrowing along the line of the pipe that travels into the house. 
Other faults can simply be the change in material from cast iron to clay; the use of plastic collars or years of corrosion has caused the edge of the iron to degrade enough that a hole appears big enough for rats to slip out of. These sorts of faults can be difficult to detect and we use a smoke generator to pump a odourless smoke into the system; if we can seal the top of the stack this will pressurise the pipework allowing us to see the smoke filter through the defect into the house. 
Usually the stack pipe terminates outside of the property and occasionally, we do have problems which we trace back to rats climbing up the inside of the pipe and simply emerging onto the roof, as the pipe has a lead surround to protect the inside of the roof from rainwater penetration, rats can slip through where the roof tiles sit over the top of the lead plate; this fault is easily fixed with a metal wire balloon but common enough that we’ll see one or two of these a year. 
In the case of faults with the durgo valve, these are internal to the house and often found inside the loft, where this is not the case, these valves will be boxed in somewhere which is pretty much inaccessible aside from cutting open walls or the boxing.  
We do find durgo’s that have been gnawed to bits by rats and these jobs can be frustrating as its not going to be our first course of action but one where we are either 100% positive or have no other option, the last thing we want to do is open up a cavity wall to find there’s nothing wrong! 
The inside of a cast iron stack pipe - easily climbable for rats 
Inside the stack pipe
Gnawed open rubber collar where the stack pipe joints the resting bend 
Gnawed open stack collar
Often hidden, durgo valves are made from soft plastic 
Gnawed open durgo valve

Faults in the underground pipework 

Depending on the age of the property, generally your house will either have vitrified clay or plastic pipe underground; older areas have proper white glazed ceramic pipe and we’ve even seen cast iron pipes taking sewerage away. These pipes can be prone to damage and collapse, the damage will often be something like a fence post punching through the top of the pipe, with any pipes nearby digging action may have struck the pipe breaking through the side and both of these allow rats to dig their way out of the drains. 
Do rats dig? Yes, that’s one of their primary ways of moving around is to tunnel out a burrow system and live underground, rats are efficient diggers and can dig down far enough to get under foundations of older properties. When the drains are already a metre underground then they have a head start. 
Older clay pipes are prone to collapse and in places like the Woodley airfield estate where the ground was heavily landscaped before the properties were built (it used to be a series of gravel pits before it was graded flat), the land is settling meaning that the pipes are placed under strain and shatter. We see lots of pipework with radial of lateral cracks and many sections that have given way, sometimes beneath the property which can be a huge concern. 
Depending where your drain fault is will depend on whether of not its your responsibility, as some sections of pipework fall under the ownership of the local water authority; just because the drains on your property, it doesn’t mean that its yours to maintain. 
The website shows you which parts of the system belong to the individual houses and which the local water company own and maintain; you can ask for a drain survey from the water company if you suspect a problem with the drains. However, they will only be concerned with their particular section of the system and our experience is that often they report back that there are no problems and no signs of rats which confuses the issue. Rats don’t leave calling cards, and often we can see no trace of them but after applying tracking dust to the drains we can tell if they have been through and so determine whether or not the fault does lie within the drains. 
If you need a drain survey, then make sure the company carrying out the inspection are members of the National Association of Drainage Contractors; they work to a high standard and a set code of conduct. We had a customer in Wokingham once who ended up calling the police to get a drainage company to leave her property; this was after they’d put in a portable toilet (at her expense) and dug up her entire patio and driveway to replace all of the undamaged plastic pipe. All this was for a pit defect that we would have repaired at no further cost as any minor repairs that we can make are included in the price of a rat treatment. 
A drain survey should include a report with time and date stamped photos of defects or a recording of the survey, another scam we found was a company in Reading show the customer stored footage of defects from the cameras memory and then bill for work that doesn’t exist. 
Collapse of a vitrified clay pipe 
Collapsed pipe
Hole in the wall of a plastic pipe 
Hole in pipe
Rat damage in a plastic pipe 
hole gnawed by rats
The website has a really good picture that shows which drains belong to the property owner and the water authority: visit their website by clicking on the button. 
Map showing drainage layouts

One way drain valves 

Finally a quick note on the latest craze – selling one way valves as a ‘cure’ for a drain defect, these can be either metal or plastic and the idea is that they are inserted into the faulty section and act to prevent the passage of rats going against a hinged flap. 
Plastic? We’ve already said that plastic is no deterrent against rats so would anyone would buy and fit a plastic valve is beyond me but they’re for sale on the internet, the metal ones work to a limited degree and can be fitted as a way of giving a customer thinking time; drain defects are expensive and generally when it includes a survey around £1000, we’ve seen repairs which stretch into tens of thousands but this was a main sewer that had collapsed under an extension and the cost was borne by Thames Water, thankfully. 
Drain valves fail for many reasons and with costs from a reasonable £60 to an eyewatering £230 (for basically the same thing) our advice is to assess the need, remember that one day you may sell the property and not notifying the new buyer of a major fault may have repercussions, as we’ve seen! 
A picture of a plastic one way valve that was fitted by a previous company; this is downstream looking at the face of the flap which, being made of plastic has been gnawed through. 
One way valve
We never charge for a drain survey – the reason is that we are not qualified to deliver what is a complex service that needs to be able to assess 100% of the system, secondly, our goal is to deliver the best pest control service that we can. The drain surveys that we carryout are all part of our service and the photos on this blog are those taken from our camera where we have pinpointed the reason for a customer’s rat problem, often within an hour of attending the job. 
Here at All Aspects Pest Control our customers are our priority and when it comes to rat control we look at the bigger picture to get the job done. 
Tagged as: Rats
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