This depends on the size of the water bottles! Here's how to figure it out:

* Standard Water Bottle: A standard plastic water bottle is usually 500 ml (milliliters).

* Conversion: There are 1000 ml in 1 liter.

* Calculation: To get 2 liters, you need 2 x 1000 = 2000 ml.

* Bottles needed: 2000 ml / 500 ml per bottle = 4 bottles

So, 4 standard 500 ml water bottles make 2 liters.

If you have different sized bottles, just replace the 500 ml in the calculation with the size of your bottle.