I'm interested in water recovery and reuse. I understand, or at least I think I understand, that even if you reclaim the water used during flat work and run it through oil separating process, that you still shouldn't put it back through your pw system because although you've filtered out the solids and the oil, any chemicals you've used are still there which eliminates downstream insertion of chemicals. The question then, is this: What chemicals used for cleaning commercial surfaces like gas stations, convenience stores, drive-thrus and banks should you not run back through your system? And, maybe an even better question, is what CAN you use?