It allows more flexibility in locating the dryer, no access to an exterior wall is needed. Also, they don't send air you've paid to heat out of the house's conditioned envelope. These dryers are also much smaller than the typical "American" dryer.
Originally Posted by bobwysiwyg
We have a condensing dryer, though ours is rigged to pump the water into the washing machine's drain. Given the gunky wet lint that accumulates in the condenser, I don't think the water from it is something I'd consider for my film, but "mileage may vary".
As for distilled from the grocery store, it's labeled as distilled, and the label further states "purified by steam distillation". Sells for right around 1 USD per gallon/3.7 L around here, FWIW.