Roebic 1 qt. RV/Marine Holding Tank Treatment is a safe and effective bacterial formulation for odor control and waste digestion in RV's, boats and portable toilets. It is non-staining and holding tanks that are treated with RV & Marine Black Water Treatment can be dumped at any dumping station or septic tank without adding harmful chemicals to the system. It is easy to use, simply add the recommended amount of treatment to your holding tank and let it work its magic.