Rats, Rats, Rats!

The beginning of the New Year has kept me busy with a common problem thread; rats entering properties through the drainage system.
Drains can fail in a number of ways: the interceptors; the point between the home waste outlet meeting the main sewer, can fail enabling rats to cross from the main sewer in the road outside your home and enter your drainage system. From here they can find weaknesses in the drain system, using their teeth to burrow out of the drains and pass into the wall cavity and from there they can pass essentially anywhere within the property.
I've used drain plugs to fit into the rodding eyes, where these bungs have been removed and not replaced, the last time, presumably, there was a blockage. This enable the rats to bypass the "p" trap within the interceptor and go over the top, where it is dry, and pass into the house waste drain system.

This is a common theme: if the drain plug is removed, from these stoneware interceptors, I believe these were pre-1960's. These older drain systems had these ceramic components fitted with an integral rodding eye to provide access for drainage rods to be used, through the rodding eye, to remove a stubborn blockage. However, it does not need saying, but I will, these systems will only work if the drain plugs are replaced after the maintenance of the drains is carried out. This could be the home owner carrying out some home DIY maintenance or it could be a professional contractor, name no names, carrying out a commissioned job, and not finishing diligently??
This image very clearly shows this interceptor, as described above. You can see that there is a waste gully with a drain "eye" above it. This the rodding eye, and it has no plug or bung in it. This means now or at some point later rats will discover this, whilst running along the main drain in the road, and will enter the through here and ultimately in to your home.
The image on the right shows a replacement drain plug installed to deny rats any further entry. The image on the right was a customer who had a large infestation of rats in her utility room's ceiling and kitchen areas. The plug was installed and the infestation was removed, after a systematic program against rats.