If you have a TDS meter you can test your ro water, you may not need to replace them. I have a meter if you want to bring me a sample I can test it for you. I am in Lawrenceville-grayson area. That is a little far for a simple test. Maybe slayer77 has one, he is in the macon area. if not you could try local shops. I would not use unfiltered tap water. That is just MHO...
good luck.