According to the WHO, tap water is safe for consumption for 81% of the country.
Bottled water is generally safe โ check that the seal is intact at purchase. Tap water in Ulaanbaatar and other cities is considered bacteria-free, however antiquated plumbing means the water may contain traces of metals that wonโt be good for your long-term health. Be cautious about drinking from streams and lakes, as they are easily polluted by livestock. Water is usually OK if you can get it high up in the mountains, near the source. If in doubt, boil your water. The best chemical purifier is iodine, although it should not be used by pregnant women or those with thyroid problems. Water filters should filter out viruses. Ensure your filter has a chemical barrier such as iodine and a small pore size (less than four microns).
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 43.23 / 100 (100 being best).
Numbeo considers this score to be "Moderate"
1 adult could save about 394$ per year in Mongolia 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.