If the water bill is $100 a month, increase the price by 20% (or whatever you decide is fair) to compensate you for the time required to split and bill and to cover additional use when tenants squander the utility.

On the positive side, it seems like you have a good potential BRRRR that you can use to purchase additional properties.

Walking score of 95.Pre COVID rental numbers:Monthly gross rent $15,250Cap rate 7.1%Future rental numbers:Estimated Monthly gross rent after current tenants move out $13,950Cap rate 6.5%Because monthly rent looks to be about 20-30% more if you rent by the month, I am considering renting out my duplex for monthly rentals on Airbnb/other sites and potentially for travel nurses (ideal because several hospitals are walking distance to my house).

Additionally, the price point is still cheap enough to find the 1% rule and positive cash flow and there's amazing appreciation potential.

https://www.nyc.gov/site/dep/environment/noise-code.page@Nathan Gesner is spot on.

Additional charges will be added to the next month's rent and due and payable at the same time.

In addition to this, I've had 2 clients this past year tell me they used Airdna in '22 and '23 to see projected and estimated income and was drastically different than actual income made with very comparable properties. 

Any business could do this with their services and the savings would certainly justify the additional effort.But if you take advantage of the new law, wouldn't the renter do the same?

It's not your fault that the tenant has to vacate, so the tenant should have insurance to protect them against any additional expenses.

Quote from @Lionel Quiambao:  ... and maybe throw in the option for the tenant for more speed at an increased rent to cover the additional payment.