dominican tap water is nondrinkable, many people do not even use it for cooking. hence hundreds of businesses selling purified bottled water.
i do not know what "filtered' means but i am pretty sure dominicans would not care whether your water is any better that water theat is already available here. competition is hard and costs are high: there is a water business right next to the plant where miesposo works, they make water and ice. just their electricy bill could give you a heart attack...