Basically, not to worry. In the hotels that I have visited, cleanliness is very important as well as hygiene. I have never had problems with water, but remember the hillbilly lives here and drinks tapwater, and has ingested river water in times of need. Who knows what is "down there" ?
But, since pathogens do not ever respect even well cured stomachs, you can be quite at ease in the big hotels.
For your walks out around the area, take a couple of pints of bottled water, drink only fresh coconut 'milk' -always opened in front of you by a machete wielding maniac (Machetes here are called "Coleens"*), never with any ice, it is surprisingly cool anyway, and stay away from "sno-cones".
If you are thirsty, do not eat fresh cut sugar cane, as you will only get thirstier!.
Have fun, I am sure you will..
HB
*Machete= "/kaw-leen/" = Dominican pronunciation of the names "Collins", the factory in Hartford, CT, that makes and exports a huge quantity of machetes to Latin America.