The drawing above shows 2,500,000 litres of water as 83.3 tanker trucks: each icon represents 1 tanker truck (30,000 litres). It is roughly what the population of the Balearic Islands (1.2M people) drinks in a day.
In other units, 2,500,000 litres is 2,500 cubic metres or about 660,430 US gallons. Change the number in the tool or pick another reference for the drawing (glasses, bathtubs, tanker trucks, Olympic pools…) with the "Show" selector.