I'm collecting all the water in the sink, I can measure the volume directly. 10 cm of water in my sink in about 13 litres. My dishwasher is specced for 16.5 - 29.7 litres on the "Energy Saver" cycle that I normally use.

(The "normal" cycle is specced for 11.0-27.7 litres but uses more electricity, which is more expensive than water.)