The PN landlord tenant act is in Title 68, Chapter 8. The UTILITY SERVICE TENANTS RIGHTS ACT is in section 399 of that chapter. I'm afraid I can't check it out for you, as it's not online yet.
Go to the library and get Title 68 and read chapter 8. Look for a listing of landlord's duties in general, and the circumstances under which a landlord can raise the rent or unilaterally impose a 'utility fee hike'.
I suspect your landlord is trying to get around rent control or a provision in the lease forbidding rent hikes. Does the lease say he can bill you for water usage? Does it define water usage? Unless the lease gives his definition of usage, a court will likely interpret the lease as allowing him to charge you for the water bill he actually paid.
Call the utility company and ask them what the water fees are for your apt. If the landlord's fee is significantly higher, tell him you will put the water bill in your own name. If you confront the landlord with the law and the hard numbers, he may decide that you know your rights too well for him to take advantage of you, and back off.
Good luck,
Tracey
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This is not legal advice and you are not my client. Double check everything with your own attorney and your state's laws.