I use the blender as well. I't has a jug with it with measurements on and I put the water in first, then plop the satchet's contents in and blend. I do it for about a min.
If its soup I use water from the kettle, just like making a cuppa, if its shake I use cold water from the fridge but I haven't tried using ice yet because im not dead keen on icy cold things. Just lately thought I have made my banana shake with hot water or warmed in the micro coz it makes me feel yummy and content.
Lynne x