Waste Water
From Captain of Industry Wiki
Waste Water is a fluid waste product produced from early petrochemical activities, or as sewage from a Water Facility. It is dangerous to your population if released into bodies of water with a Liquid Dump, causing Water Pollution that negatively affects your population's health.
With a Wastewater Treatment, it can be reprocessed into potable Water without causing pollution. If you plan to allow your population to drink the reprocessed water, it is advised that you do not tell them where it came from.
Recipes
Below are all the recipes, which contain this item. Note, that some of them may be locked behind Research, and not immediately available in your game.
Production