Soft 404
I did not received my thermistors yet (one of the last UPS update which I received by mail is An emergency situation or severe weather condition has delayed delivery. , so I will need to wait a little) but It would be riddiculous if they are not water resistant. Datasheet of every thermistor from the Kit mention that time constant is 3 second in water. So if they explicitly mention water, I gues they are designed for use in water and other liquids.
