Water infection

Myra was in so much pain I called an emergency doctor. The shiny-haired young thing was at a loss about what to do for someone who could not be diagnosed because she refused an endoscopy and who eschewed all anti-spasmodic medication. So Dr Longlocks tests a urine sample.
 
—  You have an infection in your water.
 
—  I knew there was something wrong with the water in this place.  It should be shut down. I‘m not drinking a drop from that tap unless it’s boiled and filtered. 
 
Nor did she.

Does the dementia mind become more literal or is this a case of uncontaminated logic over colloquialism?  

​Or is dementia paranoia?