We contacted ONIT about a strong rotten egg odor in our well water and spent a month going back and forth just trying to get an update.
ONIT would tell us we would get a call for updates by the end of the day, but no one ever followed up, forcing us to chase them for information. Several contact attempts went unanswered completely, and there is no publicly available email, which made communication even more frustrating.
ONIT admitted they had “never encountered this issue before” and were unsure how to fix it. Which is just what you want to hear from the people who sold you the equipment and promised to service it. After nearly a month of waiting, we were told a well specialist was needed to flush our pipes and that would fix the issue. When the technician arrived, he stated on record that he was not actually a well specialist, which means ONIT didn't even send a qualified technician.
When the tech arrived he said that pipe flushing wasn't necessary and instead identified that the system required an upstream sediment filter which had never been installed. Had ONIT just sent someone to look at our system when we first reached out, we wouldn't have been left with foul water for over a month. I'm guessing the reason they delayed sending a tech is because they do not have any in-house technicians. They hire everything third party.
If you have well water, I would recommend finding another solution as they are not prepared to handle that, and have admitted incompetence when problems arise.
If you have city water, I would recommend finding another solution because if you run into an issue you will have a hard time getting in contact with anyone.