Wet your skin and hair, turn off the tap. Then suds up without the water on. Then rinse. It can be done. But I'd get counseling on an abusive stepdad. Or shower when he isn't around!

Tell him to "step" away from you.

We used to have a 4 minute timer that would shut off the water for another 4. Trying to fill up the bath sucked. Talk to him and see if you can't get a water saving shower head and then extend the time by a few minutes :) Or try and take short showers when he's there and just wash your hair when he's not home :)

That is completely unacceptable

So fill up a bucket with hot water then have a shower ~15 min later and use the water for rinsing.

3 minutes? how does he expect you to wash your whole body and hair in 3 minutes???

Well that's a real soap opera

Where the hell are your parents?! My parents would lose it on any of their boyfriends or girlfriends for trying to take control over us. They are not the parent.

He could have at least told you about it before you showered. Even so that's a ridiculously short amount of time

Next time he does something important on the computer shut off the power after 3 minutes