You have heard the warnings before about traveling across the border: Don’t drink the water! It sounds like simple advice when traveling out of the country, but there some things that can catch you off guard and leave you very sick.

Here are 5 of the quickest ways to get sick from the water:

1. Water from the faucet. Buy plenty of bottled water to use instead in your hotel room.

2. Restaurant water. It comes from the same tap, buy bottled.

3. Ice in a glass for your soda. Ice is often made from the tap. Ask your server if the ice is made with filtered water. Filtered water ice will have a hole in the middle whereas crushed ice is likely unfiltered and chopped from an ice block made with local water. Better yet, just pass on the ice altogether. Don’t forget this when it comes to frozen drinks, smoothies and iced coffee.

4. Salad. This is a tricky one because it seems harmless enough, but remember that salad is likely washed with local tap water. When traveling out of the country I forego raw vegetables completely and stick with all cooked vegetables just to be on the safe side.

5. Recycled water. In many countries, tourists are big business. Be diligent in checking the water bottles you buy from street vendors. Dishonest vendors will simply refill used bottles with local tap water and re-sell it. Be sure to check the lid of every bottle you buy to make sure it is sealed.

It takes only a sip of water in a foreign country to make you sick. Be sure to to take every precaution before you put any food or drink in your mouth to ensure a healthy trip abroad.