El Salvador has a burdened public health system, and an excellent private system with well-trained professionals. Vigilance is required in mosquito-prone areas near the coast and during the rainy season when dengue fever outbreaks can occur.
You can easily get access to a top doctor in San Salvador, but you will have to pay significant fees up-front.
Tap water is generally very good in El Salvador; however, in poorer areas it is best to always boil before drinking.
Health insurance is highly recommended and necessary for the better hospitals.