WinterProofO Water System Antifreeze provides superior protection for pipes and waterlines during winterÆs worst conditions. With th e BurstGuardO -50 degree C Guarantee, it is ideal for winterizing cottages, RVÆs, swimming pools, boats and septic systems. Non-Toxi c. Total water system protection. Safe for winterizing plastic and metal pipes. Corrosion inhibitors. Lubricates waterlines, pipes a nd seals.