I have a counter top distiller similar to this one by H2O labs. It does a decent job, but judging from the amount of heat it puts off, and how long it takes to distill one gallon of water I don’t think it’s anymore cost efficient than buying a gallon of distilled water.
During the winter I literally raised the temp in my small apartment by over 5 degrees while running it. I ran it last week and it brought my indoor temp up over 10 degrees. If you live in an area that has hot temps, and your domicile doesn’t have air conditioning I would recommend biting the bullet and buying distilled water. My apartment during the summer, with air conditioning, averages around 67 degrees. I ran it yesterday and it was 78 degrees inside.
tldr: It puts off a lot of heat, and takes over 5 hours to distill a gallon of water. Zero Water makes a pretty dang good filter, and @Stephen has mentioned that it is sufficient for growing as it removes all dissolved solids.