I'm trying to think back to my high school science classes (which was a distressingly long time ago). If I remember rightly, detergents and soaps involve a lot of nitrates. Nitrates are also used in fertilizers and (again, I'm trying to think back over twenty years), the quantity of nitrates washed into the water system from soap and detergents is a serious pollution problem. So, a thought crossed my mind when I was washing the dishes the other day. What if I watered my houseplants with old dishwater? Would this be a way of fertilizing them?
Detergent and soaps do not involve a lot of nitrates. Detergents and soap contain a lot of phosphate. Millet (1,288-) Susan B Anthony List - Washington DC
