*PLUMBERSSTOCK EXPERT* responded:
Good day! Thank you for your interest in our Norwesco 40631 Above Ground Black Water Tank. According to Norwesco, it is recommended that this tank be used for water only. For more details, you may want to check this Specification Sheet. For black and grey water, it is best to use the white premium weight tank because they are made with a higher specific gravity of 1.5 instead of 1.0. If you need the same gallon capacity of this, you need to order the Norwesco 40051 White Vertical Storage Tank. You can check page 3 of this Specification Sheet for more information. And for more options, here is the Catalog for the lists of Norwesco White Premium Weight Tanks. To order a product, go to its product's page, just click "Add to Cart" and put your postal code and you're ready to go. If we can be of any further help, feel free to contact one of our customer support specialists at 435-868-4020 or through e-mail @ firstname.lastname@example.org. Have a wonderful shopping!