I'm afraid I can't help you with the panty stain problem but I can offer a recommendation for the Water Works system. It is pricey but well worth it, believe me. I have been using it daily for several months and I have not had a trace of any yeast infection or itch, any vaginal odor at all or even any everyday discharge, so there is nothing that would stain panties. As a matter of fact, I have never felt so comfortable and confident wearing skirts with no panty at all (commando) and I have convinced two of my friends to invest in Water Works. They are as happy with the results as I am. And it is easy, pleasant and fun to use. What a great invention!