Short Answer: After bankruptcy discharge, you are still responsible for the HOA fees (accrued after filing bankruptcy) because that is a new debt. If you continued using the water, any water bill is also a new debt incurred after filing bankruptcy so you will have to pay that as well.
Long Answer: If you are letting this house go anyway, these problems are often manageable through a shortsale process, where you can often end up receiving money to sell the house. If your name is still on title, you should consult an attorney about a possible shortsale. Depending on the type of loan you have, there is often a sizeable chunk of money available to homeowners in your situation.
this is a problem we see all the time. People file bankruptcy and surrender their homes, but unfortunately, their liability may not completely end until the bank retakes legal ownership of the house. You are right to think you are responsible for the HOA bill even after bankruptcy, and probably the water bill as well. However, if you are on a fixed income, it's possible that you are judgment proof and wouldn't have to worry if you stopped paying? It's something to think about.
A horrible situation! And increasingly common, unfortunately! Start by consulting your bankruptcy lawyer. HOA fees for the time prior to your bankruptcy should have been dealt with in your proceeding. Post discharge HOA fees continue to be your responsibility. But if you stop paying these bills (including the water bill), the charges will eventually become liens on the real property. But forcing your lender to foreclose is a tricky thing--under current laws, a lender is not required to foreclose, even if you move out and really, really want them to take the property.
Unfortunately bankruptcy does not discharge your liability for the debts that arise after the date on which the bankruptcy case was filed. A discharge under Chapter only discharges you from "debts that arose before the date of the order for relief..." 11 USC Sec. 727(b), and specifically there is an exception to debts for a "fee or assessment that becomes due and payable after the order for relief to a membership association with respect to a debtor's interest in a unit that has condominium ownership in a share of a cooperative corporation, or a lot in a homeonwers association for as long as the debtor ... has a legal or equitable interest in such unit, such corporation, or such lot..." 11 USC Sec. 523(a)(16). So long as your name appears on the title of record to the property, you would remain liable for any debt arising after the date your bankruptcy case was filed. If after the property is sold at foreclosure, and thus no longer in your name as owner of record, if a judgment is obtained against you and your assets (such as your wages or bank account) are attached, you could file a Chapter 13 case -- which would create an automatic injunction, and if the filing date was more than four (4) years after the Chapter 7 case was filed, you could obtain a discharge of these debts (it's eight (8) years to be able to file another Chapter 7 case and obtain a second discharge).
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