Earlier quoted context omitted.
You can use liquid soap. And for dry soap I tend to just open the water a couple of seconds, close it, soap my hands and then wash it away again. There's really no need to let the water run all the time, that's a waste.
If your goal is to actually clean your hands, then it's not a waste. Proper hand-washing requires not touching anything dirty after you've cleaned up. And how did you turn the faucet on? With your dirty hands. So, wash, dry with a paper towel, turn faucet off with paper towel.
Being too much of a maniac with such thing is no good. Especially not for your kids: an environment that is too clean will prevent them from developing proper defenses and as soon as they'll be outside, they'll get sick like sissies all the time :-/