Supposedly,I'm on my own hot water tank however ,I lose pressure when laundry room in use in 4 apartments building,my utilities bill sky high ,how do I find out if I'm paying laundry room utilities?

Oh and utilities in there name I pay bill

Get a plumber in to track down the piping. Sure sounds like you're paying for everyone's laundry. What bill? Water or electric? Have you thought of turning the water off to your water heater when you hear them doing laundry? Back to you, Tom