I do love the idea that they chuck sodium fluoride in the water because its cheaper than "proper" disposal. That one cracks me up, it costs the water companies to add it. The site I worked at until 6 months ago had several million £££ of chemicals in the warehouse, many would fit your idea of "waste", none were free. One of our most widely used would cost around £2000 for a standard barrel, yet it was basically a by-product