Having said all this, you may want to skip using water coolers altogether. If you have one in your home and you clean it regularly, you’ll be totally fine. But if you share a water cooler with colleagues, you may be able to get sick.
Even if a shared water cooler is cleaned daily and sanitized weekly, your colleagues may not always have clean hands before they touch the taps (source). Germs and bacteria can quickly build up on the outside of the water cooler and contaminate the water or your drinking glass.
Common bacteria found in workplace water coolers include germs that can cause Legionnaires’ disease or Pontiac fever (source).
So even if you know exactly how to clean a water dispenser, germs can still fester. If your company has invested money in a commercial-grade water dispenser, it’s a shame, but better safe than sorry.