Is $20 a day realistic for a whole month?

Yes, provided you don't stay in one city the entire time. The cost of living is lower in the north and central regions than in Ho Chi Minh City.

Can I drink the tap water?

No. Always use a filtration bottle or buy 5-liter jugs of water to refill a smaller bottle to save money and plastic.

Vietnam on a $20 Daily Budget

You can comfortably survive in Vietnam on $20 a day by sticking to street food, staying in hostel dorms, and traveling via local buses. Avoid private taxis, western-style restaurants, and tourist-heavy tour packages to stay within this limit.

Choose your accommodation wisely. Book hostel dorm beds that cost between $5 and $7 per night. Use apps like Hostelworld to find places that include free breakfast or free beer hours, which can save you an extra $2-$3 daily.
Eat exclusively from street vendors. Stick to Banh Mi, Pho, and Com Tam sold on street corners or in local markets. A meal should cost between $1 and $2. Avoid 'sit-down' restaurants with menus in English.
Use public transport or walk. Download the Grab app to check prices, but opt for local city buses whenever possible. For intercity travel, book 'sleeper buses' via agents or hotel desks; they are cheaper than trains and save you the cost of a night's accommodation.
Master the 'Free' lifestyle. Focus on free activities: walking through historic quarters, visiting public parks, swimming at public beaches, and exploring local markets. Skip high-entry-fee museums and private boat tours.

Is $20 a day realistic for a whole month?: Yes, provided you don't stay in one city the entire time. The cost of living is lower in the north and central regions than in Ho Chi Minh City.
Can I drink the tap water?: No. Always use a filtration bottle or buy 5-liter jugs of water to refill a smaller bottle to save money and plastic.