Yes if they hooked up the unit in reverse it push the media into the water lines of the house,Health wise you should be fine,But someone will have to remove this media from all the lines or you volume will diminish at your fixture's as the media will clog them to all is removed.
I should have given you a little more detail - this system was installed in a small rural community that includes a restaurant, motel, store, and water supply for some of the local residents that use the water for their livestock. We have a heat pump system that heats and cools our motel rooms, a fire sprinkler system, and several homes for our employees. We have a small water processing facility and waste water processing facility so its a larger scale problem. I am afraid that the installers are trying to disassociate themselves from the problem. I have been asking them about Culligan's protocol for an incident like this and all I am getting back are other possible reasons for the media loss. They measured the remaining media in the two tanks and are telling us that they are only missing about a half inch from one of the tanks. It seems to me we have been recovering more than this from the blockages in the homes, our community water system, etc.. but a little bit of this stuff seems to be able to cause a lot of problems - especially in valves and anywhere the water passes through a screen.
I have been looking for a spec sheet or a detail of exactly how the water moves through the tank and the arrangement of the gravel, media, etc.. in the tanks but can only seem to find installation specs.
They are saying that running the water through the system backwards would not cause the media to exit in to the water system. Thats what I wanted a second opinion on, so thank you for that.
The other reasons that they are putting forward - high chlorine levels, cold temperatures, air bubbles in the water from our pressure tank, don't seem to be holding up. We have not had cold temperatures or high chlorine levels and air bubbles don't seem particularly prevalent. I am not getting any recommendations or protocols from the installers on what to do about this stuff in our water system and I don't know what to do next. Would you recommend that I contact Culligan's corporate office and ask them their protocol in this situation?