water drinker

noun3

1. •
   Someone who drinks water, especially in preference to alcoholic drinks; a teetotaler.

   • Could not resist Metcalfe's fine dishes and wines. Sir Joshua began to be a water-drinker. — 1789
2. •
   (historical) Someone who drinks the waters at a spa.
3. •
   (no longer used) A member of an early Christian sect which drank water instead of wine during the Eucharist.