In major urban areas tap water in Belize is considered safe to drink. Outside larger cities and towns, hotels may use wells or rainwater collection tanks in which case water should be boiled or treated.
Many hotels will provide drinking water for guests.
According to the CDC tap water is generally not safe for consumption.
According to the Numbeo water drinkability and accessibility index, tap water has a score of 66.67 / 100 (100 being best).
Numbeo considers this score to be "High"
1 adult could save about 657$ per year in Belize by drinking tap water instead of buying bottled water.
๐ณ Drinking tap water would also help with reducing your plastic footprint and improve environmental pollution.
Like in most countries, water quality and accessibility differs from location to location, therefore it's the best to check the information available on that place.