Using a UPS for other things

Over the holiday weekend I went over to my parents' house to help my dad with his battery backup sump pump. He purchased a Basement Watchdog a few years ago to protect his basement, but we have become disappointed by the amount of service it needs. The battery needs to be opened and distilled water needs to be added to the sulfuric acid every 6 months. My dad doesn't feel comfortable doing this so I have to help him. The first battery completely failed after two years and cost $95 to replace. For that price I am considering buying a computer UPS system and plugging in a standard sump pump. Has anybody tried this? Please feel free to share any other UPS applications you have tried in the past.