I was called to a job in Ferny Hills this morning to make a power point and light switch safe as the owner is replacing his ensuite bathroom. The reason is that rats chewed his plastic water pipes which then wet all the internals of the wall and floor. It is partly covered by insurance so he is not totally out of pocket.
We were talking about the course of action to get rid of the rats and he said he was going to bait the roof and put up a bowl of water so they do not chew the pipes and I suggested the opposite. Just bait them and they will go out looking for water and die out side. This also eliminates the possibility of them dying in the cavities and making the house smell terrible for a while.
I found a link that may also be useful:-