try your local Walmart ,some have ro water or distilled water by the gallon.If you buy an ro unit you can get buy with a 24gpd unit,drain into a rubber maid or large garbage can, with a power head and heater,make sure you buffer the water as you will use as top off water (most ro water will be in the low 6's for a ph)save your money don't buy a tap water filter,most any hardware you buy shop on line.