Indwelling Catheter

I have question about the water volume in the balloon. When changing the catheter, I withdrew 7 ml water from the old balloon, and he was an elderly. But we are supposed to inject 10 ml. I didn't see his chart said anything about the water in the balloon. What should I do? Inject 7ml in instead of 10?
The balloons deflate over time losing water by osmosis, follow the orders or if not specified, what works for the individual.

Quote from Libby1987The balloons deflate over time losing water by osmosis, follow the orders or if not specified, what works for the individual.