Water is rising out of our bathroom sink when the AC runs. It gets worse over night since that is when the AC is set cooler. Closing the drain does not work, and I have used many drain cleaners. I just want to know if here is more permanent solution because last night the sink was full. Thank you for any assistance!

Clean the house drain line as it is most likely clogged. Why don't you just drain the condensate outside?

Clean the house drain line as it is most likely clogged. Why don't you just drain the condensate outside?

Thanks for your response. I don't have any experience with AC units so could you clarify when you say drain the condensate outside? Is there anything I should look to clean out in the unit in the attic?

The water (condensate) in an attic unit is almost always drained out a wall pipe to the outside. Don't know why it is run into a house drain. I have seen condensate pumps run into a house drain but never a gravity flow drain. However, if the water is filling the sink, you must have a blockage in the drain after the sink. Does the water run out of the sink when the stopper is opened? Water flows out the overflow drain hole in the sink?