In short, the potable hot water argument for a combi in a domestic
situation is a very thin one.

However apparently you *can* drink it, if that is important to you.

Actually, I use the potable nature of instantaneously heated water quite a
lot. I always fill the pan from the hot tap when cooking vegetables or
pasta. Saves quite a few minutes. My system isn't a combi, though. It is a
heat bank, so has no trouble with 40lpm+.

Christian.