We have been renting out my mother in laws house. The renters left a leaky pipe for two months without saying anything. Now the water bill is over 1,200 dollars.
We can't pay it all in one lump sum. If we can't get on a payment plan and the water gets turned off. What damage will that do to the water tank?

I assume if it is gas , you have turned the gas off to it, if electric you have turned the electric off to the tank, if there is a separate valve you turn the water off to it and drain it.

Have you sued the renters for the money ?

Why is or was the water in your name and not the renters name ?

We were told it was up to the rentees to pay the water, and the renters to pay everything else. They packed and left, have no idea where they went. You live and learn I guess.