How much water should be

Question

How much water should be put into a Dimplex Portable Air Conditioner DAC15HH? The user manual does not say how much. There is a clear strip on the side which runs the full height of the unit which allows you to see the water level but does not have a marker to show how much to put in. I added water to reach a few inches up the gauge, then the "empty the water" symbol and "dinging sound" came on. I switched off and it leaked all over the floor, even though the outlet plug and cap were still in place