If you are cleaning bins for money then you need to seek authorisation from your water company. In practice this means that you need to contain the wash water used and dispose of it in a sewer drain at your base. This way the water company can test the water and trace where contaminants originate from. Oh and they can charge for it!!! However, in this really doesn't cost much, in my case about 140 quid for authorisation and so much per cubic metre each quarter. If you dump the wash water in the street then you are breaking the law....