How about the bathroom?

Experiment with timing the family’s baths and showers. Short showers use less hot water than baths. Are your showers longer than say, 5 minutes? Your gas water heater will work more efficiently if you try to shorten those soaks. Make a chart to record the times over a period of a week. It should then be easy to see who is taking the longest to primp and look pretty - could be revealing!