The municipal water supply in Suva, Nadi and other large towns is chlorinated and can usually be trusted, but elsewhere avoid untreated tap water. After heavy rain itโs worth boiling the water before you drink it.
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 70.59 / 100 (100 being best).
Numbeo considers this score to be "High"
1 adult could save about 1015$ per year in Fiji 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.