Oh Dear, Oh Dear!
I just used "Fairy liquid" as a generic term.... I doubted anyone would have heard of "Ecover liquid"..........
The only time I've seen it done was in a Marina when the owner sprayed some onto a diesel leak to prevent it staining all the sides of the shiney new boats there.
What do you do with the washing up water, then? Yes, of course, you could empty it into the loo, I guess.