The extra energy required to heat the incoming water is probably more wasteful then just running your RODI
straight from the cold water supply line. That 2% statistic per 1 degree is probably not exact either. I have my unit in the garage inside a cabinet and sometimes the garage door is open to the winter cold all night and I don't see that much drop off on my product water. Also as mentioned before it doesn't matter whether you have galvanized, PVC
, PB, ,pex, copper, etc for your water piping because the filter removes the impurities and particulates.