The discovery of sewer rats is often a symptom of other serious structural drainage and sewer problems building up.    Blockages caused by incorrectly flushed household items and food waste build-ups will attract rat infestations into your sewers. 

Exjet has a range of services including CCTV Drainage Surveys and Drain Unblocking that can help. 

About Sewer Rats

Sewer rats are a common species of brown rat (Rattus norvegicus). They inhabit the sewer systems of many urban areas around the world. These rats are well adapted to living in environments with high levels of moisture and limited access to food sources. They have also developed strong swimming abilities that enable them to navigate through the water-filled tunnels of the sewer system.

a large rat foraging in sewer and drainage

Sewer Rat Problems?

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Why Are Rats Attracted to Sewers?

Sewer rats are attracted to sewers for several reasons. Firstly, sewers provide an abundant supply of food and shelter for these rodents. Sewers contain organic waste and other debris that can serve as a food source for rats.  Also the sewer tunnels provide a safe and secure place for them to live and breed.

In addition to food and shelter, sewer rats are also attracted to the warm and moist environment of the sewer system. This environment is ideal for the rats to thrive and reproduce, as it provides the optimal conditions for their survival.

Sewer rats are known to be carriers of many diseases that can be harmful to humans, such as leptospirosis and salmonellosis. As such, it is important to take measures to control their population and prevent them from spreading disease. This can include sealing off entry points to the sewer system, eliminating sources of food and shelter, and using traps and baits to capture and remove rats from the area.

Sewer Waste Build-Ups and Blockages

Sewers are designed to handle human waste and water.  However in the vast network of pipes and chances are you’ll find much more than this.

Items that people shouldn’t flush down their toilet, such as nappies, condoms, wet wipes and cotton buds, are all prevalent in sewers.  Sewer workers have also discovered prosthetic limbs, false teeth, clothing, footwear and even larger objects.

Large chunks of congealed fats and grease, known as fatbergs, are also commonly found in sewers.  A whopper of a fatberg was discovered in London, measuring 250 metres and weighing 130 tonnes.

Anything that shouldn’t be in the sewers can cause an obstruction, potentially causing water to back-up and flood into homes. It costs local authorities around £70 million every year to remove 300,000 blockages caused by items that shouldn’t be there.

Fat blockage exposed in a section of drainage pipe

Hardened Fat Build-up in Drainage Pipe

Sewer Rat Population

It’s estimated that there are at least 200 million rats living in sewers in the UK. These sewer rats, also known as  street rats or Norway rats, happily live in the underground network of tunnels, where they can easily move about, forage and breed. As creatures of habit, sewer rats establish and explore trackways through pipes, which they mark with their urine.

Sewer rats are tough and resilient creatures. They can go without food for four days and survive being flushed down a toilet. As strong swimmers, their legs make great paddles and their long tails serve as rudders for steering. They can tread water for up to three days, swim for up to a mile and hold their breath for three minutes.

Populations of sewer rats converge near urban areas, as there’s more food waste for them to consume that collects near drainpipes. If food sources dry out, rats will even eat faecal matter.

With their hinged ribcages allowing for easy movement through pipes, it’s not unheard of for sewer rats to find their way into your toilet bowl, although, thankfully, this is a rare occurrence!

Why Sewer Rats Have a Bad Reputation

Rats are easily one of the most despised creatures on the planet – and it’s easy to see why.   Associated with transmitting diseases to humans, they also have a bad reputation for gnawing through wiring and causing electrical faults. Did you know, rats are also thought to be responsible for depleting a fifth of the world’s annual food supply?

Rats have also long been blamed for spreading the Black Death plague during the 14th century and the Great Plague of London in the 17th century.  Allegedly this was caused by rats carrying fleas that bit humans, transferring harmful bacteria. However, recent studies have suggested that it was more likely human fleas and body lice that were the culprits, as opposed to rats.

One could argue that sewer rats provide a useful role by consuming waste that would otherwise contribute to blockages.  We think that the jury is still out on that!

The Rise of the Super Rat?

The average adult brown rat measures around 40cm in length and weighs about 350-500g. Recently, there has been an increase in sightings of rats much bigger than this, often resembling the size of a cat or small dog. In particular, a large rat measuring four feet long was discovered near a children’s playground in London.

Some scientists claim these so-called super rats are increasing in size because rodents are becoming immune to poisons. A researcher from the University of Leicester even claims that super rats could one day become bigger than cows!