For your hotels in San Jose, or any major city such as Alajuela, Heredia or Cartago it is safe to drink tap water, this is also true for most of the more mountainous regions you may visit, such as Monteverde, Arenal or the Savegre area, where the water is not only safe but, in many cases, exceptionally pure.
If you’re in a lowland area or down on the coast, you should be more wary. Ask if the hotel has filtered water and if not, stick to bottled. This is especially true on the Caribbean coast, which is generally less developed. The hotels will normally include a sign saying whether the water is safe or not, in most cases, it is!
We wouldn’t say you can drink the water anywhere; be careful in the lowlands and never ever drink water from rivers, streams or waterfalls.
In most locations the tap water is clean, and if you follow the geographical guidelines above you won’t have to worry. And if you’re unconvinced, bottled water is cheap and available, and our staff will be happy to procure it for you.