Thetford Campa-Fresh? Free and Clear 32-oz. The advanced-action triple enzyme black and grey water holding tank treatment is formulated for RVs boats and portable toilets. Designed to neutralize odors our enzyme-powered formula Free & Clear 32-oz ensures efficient waste digestion while preventing clumping clogging and tank residue buildup. Formaldehyde and Bronopol Free our RV toilet chemical is safe for marinas campgrounds and septic systems meeting California compliance standards. Septic system safe in easy dosing format: 8 oz of Campa-Fresh? treats a 40-gallon tank; 8 doses per jug.