Gray Water Tanks For wastewater storage and transportation. For black water storage, the problem concerned the most is the leakage.  So how to make sure the quality is the point.  Flixtank gray water tank is produced by heat melting machine, the temperature reach to 600-700 degree and melt the PVC fiber and pressure sheets together.  In this way, it can prevent the leakage problem which caused by glue sealing tanks. The wastewater tank, size ranges from 100L to 200,000L, popular sizes: 1000L, 5000L, 10,000L, 20,000L, etc.  Custom Available, contact the factory direct.