On my NYC DEP bills it says:There doesn't appear to be a service fee component (though I suppose minimum daily rate mimics that to some extent). I believe the current rates are $4.10 per HCF (hundred cubic feet, which is 748 gallons), and wastewater is 159% of that - for a total of ~$10.62 per HCF.
That's pretty average. Actually surprising because NYC is usually much more expensive.
To check you toilet for leaks, flush the toilet and while the tank is refilling put a few drops of food coloring in the tank. Come back 10 minutes later, if you see any color in the bowl it means it's leaking.
Another test is to just turn off the water supply to the toilet, but it will take a few hours to see the level in the tank go down.