Usually confused with Brown Rats, these small, blunt-nosed rodents can occasionally enter buildings, but normally live in outdoor burrows. Not regarded as a household pest, and in fact, some species such as the water vole are a protected species and cannot be harmed.
They are harmless, and no treatment is necessary. However, unless you are experiencing a high volume of these in your house, then we would suggest doing nothing.
Use a trained professional pest controller.