I just got my 4 stage BRS plus RODI setup last night and tried it out. After running for about 30-40 minutes i checked the input and output. I got 0 on output so thats all good but I was surprised to see input TDS in the range of 1-3! Ive seen people on here claiming TDS input of over 100. Do I just have clean water coming from the city? Do I still need the RODI or can I return this and just use tap?