I have received differing opinions regarding the proper method to maintain the condensate drain on a A/C unit. Some say it is OK to “flush” the drain periodically with a bleach solution – and others indicate that bleach could damage the drain piping and the proper method is to flush with vinegar.
Looking for “expert”/experienced guidance.
Thank you.
Chuck
Diluted bleach should not hurt. Remember, bleach comes in plastic bottles 
Diluted bleach should not hurt as stated above. However, plain white vinegar can be used with very good results. It is also much safer to handle and can be used undiluted. When asked by clients what to use for jetted tubs I tell them what we do. We use a gallon of white vinegar at least once a month and run it through the jets for 15 minutes. It cleans very well and will not damage piping, joints, nothing. White vinegar is also less liability for a proposed solution to a client.
If it is metal drain piping I would not use bleach myself. If it is pvc piping bleach or vinegar is fine.
I am leery myself on telling people to use bleach on anything as some people are not to be trusted with any chemicals what so ever. 