Hi Lee
I use a 200gpd RO.
TDS into the RO 420... TDS out of RO.. 8. SO:
500000/8 = 62500 ltrs total pure form one 25 ltr bag of resin. 300 ltrs per day x 5 days a week = 1500. So. 1 bag of resin lasts me for over 41 weeks work per man. Actually its about a year because we use more like 200 ltrs per day per man.
Hope this helps
Andrew