You shouldn't drink tap water directly.
TL;DR: No, it's safer to use boiled or bottled water instead.
If you're visiting from a Western country, you're likely accustomed to drinking tap water directly. However, in Vietnam, even though cities like Da Nang officially state that tap water is safe to drink, it's advisable not to drink it directly.
Tap water quality in Vietnam has improved significantly compared to 20 years ago and is generally acceptable. However, there's always a risk of bacteria or other contaminants, so boiling water is recommended. Here are your best options:
Almost every hotel and apartment in Vietnam provides a kettle. Use it to boil tap water before drinking. While heavy metals and significant chemical contamination are uncommon, boiling helps eliminate potential bacterial threats.
Bottled water is easily accessible in grocery stores and convenience shops. A typical 1.5-liter bottle costs between 10,000 - 15,000 VND (approximately $0.50 USD), making it an inexpensive and convenient option.
Purchasing 20-liter water bottles is a popular and economical choice, especially for longer stays. However, be cautious and select reputable brands such as Lavie. Unfortunately, some providers refill these large bottles with tap water and sell them fraudulently. Always buy from trusted, verified suppliers.