Main emergency helpline (with a bilingual operator) 1500
If possible, don't rely on the public healthcare system in Guatemala. It's extremely underfunded and the quality of care is not high. Rather, invest in travel insurance that can cover you in public hospitals, which are more modern and offer significantly better care in Guatemala.
Travel insurance isn't mandatory, but recommended. Choose a plan that offers coverage for Covid-19 and unexpected quarantine. As mentioned, treatment in private hospitals can be expensive if you don't have insurance coverage.
*this information is taken from the official CDC website There are no vaccinations required for entry to Guatemala but check with your doctor if they recommend taking additional ones against:
Hepatitis A & B
If you're traveling from an area where yellow fever is common, you will need to show proof of vaccination against it.
No, you should not be drinking any tap water in Guatemala. Stick to bottled water for drinking and brushing your teeth.