[ossiblue]

Sorry, no advice but I'm following this thread. We currently have copper piping which is exposed under the house. Naturally, after 30+ years with our water quality, some leaks happen and our good friend, a plumber, recommends a PEX re-plumb. My first question to him was about rodents/vermin since that is an issue in our area and we've had them at our house in the past. I was not comforted by his reply which was, basically, yes, they can/will gnaw through the plastic pipe.

For you, I see no way to deter unless the pipe is in a protective conduit, but would that be worth it or economical? As a layman, I'd say pest control is your only prevention.