I was watching Ask This Old House this morning.
They installed a high efficiency combo boiler and WH, a neat little unit that hung on the wall. Rich pointed out the condensate pump and the Limestone Neutralizer cartridge stating that the condensate water can be acidic. He noted that the pump sends the condensate to the sink.
Why do we have to be concerned about acidic condensate going down a sink drain? Could it be septic tank related? They didn't say anything about a septic system.