Two five gallon buckets with one or two gravity feed high end carbon ceramic filters will quickly filter rain water or any water source other than tap water without waste without toxins or bacteria. Water needs to be at room temperatures. This type of filter is about 120 dollars. You will have a product that is not full of toxic fluoride with heavy metals. Fluoride is a carcinogenic poison right, you all know this right, and plants absorb it readily. Fluoride also makes people passive and dims their thinking. RO does not remove it at all, neither does carbon.