If your children are like most, all sense of time goes down the drain while showering. There’s no such thing as a “quick shower”.
You can still take control of the water situation however.
Install a shower timer in the kids’ bathroom. Usually this is a battery-operated device that limits showers to your configured time, such as 5, 8, or 11 minutes.
Reducing shower time can easily save you over $200 per year.