I've seen some portable a/c units that have a tank (sort of like a dehumidifier) and some that have a built-in pump that I think might be more reliable. I bought a Whirlpool unit for my mother that had a tank, and I bought a low-profile condensate pump to move it outside. I got it last year as a floor model for $99 on a $550 unit. Seems to work fine. If the humidity is very high, unless it is being pumped outside, I think any unit might be subject to problems if it relied on evaporation of the condensate to evacuate it in the air stream.