Professional Pest Controller Magazine Issue 93

06 December 2018

The case for rat blockers

Prevention | PPC93 December 2018

Rats love drains. They’re a hidden highway to access property unseen and cause costly damage to property and health concern for the occupants.

Daniel Bamford, Director of BPCA member company Metex, explains how a properly installed rat blocker can protect your clients from reinfestation and add another potential revenue stream for professional pest controllers.

The case for rat blockers

Rats get homeowners understandably stressed and agitated, thereby keeping professional pest controllers on their toes. However, by not investigating drains and fitting a rat blocker, some pest controllers are missing a real opportunity. Not only could you be addressing a potential rat entry point, but you could make a decent add-on sale, and most importantly keep your customer happy!

Drain defects are common and can give rats convenient access to a property. Defects may be caused by ground movement associated with tree roots settlement, or old drains being built over, which regularly happens with properties that historically had an outside toilet which was subsequently extended.

Rats accessing a property that is in otherwise good condition causes distress to the homeowner. They are often heard in the wall cavities and roof space but can also chew through flexible pan connectors behind a toilet. On rare occasions rats are even gaining entry by swimming through the u-bend of the toilet and, in parts of the Mediterranean, holiday home owners are known to leave the toilet seat down, secured by the weight of a brick when they vacate the property to prevent unwanted guests.

Quality rat blockers are a powerful and easy to install device that quickly eliminates drains as a point of rat entry.

Rat blockers are simple, robust devices that act as a one-way valve for rats. They are inserted into a drain to prevent the movement of rats towards a property while allowing the drain to function as normal. With pest controllers discovering their benefits, the use of rat blockers is on the rapid increase in the UK.

Lessons from Denmark

Rat blockers are firmly established in Europe and particularly in Denmark, where they are routinely fitted, partly due to the strict restrictions on the use of rodenticides there.

Rat blockers are now actually required by legislation in Denmark and, as a result, are fitted in every school, government building, hospital and new property. With more than 100,000 rat blockers installed they are considered mainstream, acknowledging that prevention is better than cure.

Mikkel Dahl Hanson of Nordisk Innovation, a rat blocker manufacturer, states that up to 90% of town rats in Denmark come from underground pipes. With public complaints on the rise, there has been a mind shift in Denmark from the belief that rats can be eliminated completely to the understanding that to control a population they must be blocked from access to nesting sites.

At the beginning of October 2018, TRYG, the largest insurance company in Denmark, began to offer premium home insurance policy customers a free Nordisk Innovation rat blocker, including the cost of installation. This bold move by the insurance industry acknowledges that rat blockers give homeowners peace of mind and have the potential to save the insurer money in the long run.

Some of the best rat blockers on the market are ‘VA Approved’, having passed a series of rigorous tests at ETA-Danmark. The test criteria include flow tests, as well as placing a rat in a sealed system for two weeks with a rat blocker separating them from a food source, a small fan is introduced to waft the food smells towards the rat, and in order to the pass the test the rat must not be able to pass the device.

The case for installing a rat blocker

Rats within drains will seek access to smaller diameter pipes due to the lower flow rate when looking for a dry place to nest, and a rat blocker is a practical measure to prevent this. They are non-toxic devices, immediately effective, and can usually be installed within minutes. With installation complete in a single visit, they are effective even if there is an unseen drain defect, and may negate the need for expensive drain repairs.

Typical rat damge and a rat blocker fitted in a drain

High-quality rat blockers can be installed from street level by way of an installation pole without the need to consider the health and safety aspects of entering a confined space.

Fitting rat blockers results in more satisfied customers, and a good financial return for the pest controller. And, once installed, there is an opportunity for repeat visits as part of a maintenance contract.

Pest controllers who start using rat blockers for the first time, usually see the frequency of use increase quickly as they start offering them as an add-on sale where evidence of rat activity in the drains can be seen, or to give customers peace of mind.

Residents in new housing development “hell” following “rat infestation”

This was recently reported on a BBC Devon website and, after spending thousands of pounds in failed attempts to address the issue, residents contacted BPCA member, ISCA Pest Control. Dan Schofield quickly identified the drains as the source of the problem and fitted two six-inch Nordisk Rat Blockers.

The residents are delighted as there has not been an issue since. Dan frequently comes across this sort of problem which he says is relatively typical for new build properties.

ISCA estimates fitting twice as many rat blockers as this time last year, with 100% customer satisfaction.


Quality rat blockers are robust stainless steel devices that will give years of trouble-free service. However, it is essential that they are checked and cleaned at least every 12 months.

Uncontrolled debris, food waste, sanitary items and wet wipes are often present in drains and can cause blockages elsewhere. Therefore it is essential that an installed rat blocker is not blamed for drain issues caused by these other factors.

In conclusion

Rat blockers are widely available from pest product distributors. There are good quality units on the market, but it is important for pest controllers to make an informed purchase and to be able to stand behind the product fitted. They are an extremely useful tool, but it should be noted that they must be used as a part range of treatments to ensure rats already within a property are removed completely.

Daniel is the Technical Director of Metex and is happy to advise pest controllers on rat blockers.

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