Give him an opportunity to pay you back for the bill if he doesnt pay in 7 calendar days tell him you are going to file a claim against him in municipal court for the bill. You may do that yourself or hire an attorney and the landlord will be forced to pay the attorneys bill if that is stated in your lease
Contact me for further detailed questions and answers. 215-561-0877 DISCLAIMER: Matthew Solomon is licensed to practice law in both the State of Pennsylvania and the State of New Jersey.This answer based on general legal principles and is not intended for the purpose of providing specific legal advice or opinions. This answer does not constitute the establishment of an attorney-client relationship.
The landlord's interference with your water usage is a breach of your quiet enjoyment of the lease and may violate other lease provisions as well. You may give the landlord written notice that you are withholding the amount you paid for the water bill from the next rent payment unless he reimburses you beforehand. (Just be sure it is money he actually owed). It is not feasible to take legal action to compel him to pay the bill, but if he would attempt to take action against you for withholding the money from your rent, it seems to me you should have a pretty solid defense.
A full legal opinion and firm recommendations can only take place in a formal consultation with an attorney. These are my general thoughts given the limited information presented and for the purposes of this online forum only. No attorney/client relationship exists.
Look at your lease, it likely has a provision relating to repairs that will allow you to pay the bill and deduct that amount from your next rent payment. You may have this ability for other repairs as well.