We have a dehumidifier (we live in the southern hemisphere) and I was wondering if the water from that would be ok for the plant? Also, do I have to put it in the fridge (because it is our winter) to give it a dormant period?
Airconditioners and dehumidifiers both create condensation by cooling air blown over the coils. The only thing that I know of that might cause problems is if they are dirty which may spread fungus spores to your CPs when you water them. If the drip trays, coils, and hoses are kept clean, that would reduce the chance of giving your CPs a case of the creeping crud.
I agree with BCK, as long as it is kept clean, you will be AOK.
I would also, if worried aboug fungi and mold, microwave or boil the water... (microwave is probably better... nothing kills like cosmic rays right!?
but yes, as long as it is kept clean, and you make sure your not watering with dust and other particulates, I would say your doing A OK, and you could always run it through a paper coffee filter to get the larger matter as well..
but one thing is certain, unless you have a lot of mineral dust floating around your house (live near a rock quarrey or something) your getting a very clean form of water.