Any private water supply to a food premises (eg, game larder) is required to be of potable standard. It has to be tested and, if necessary, a water treatment system installed. Obviously this wouldn't apply where carcasses are only ever used for personal consumption, but any larder that holds deer prior to onward sale will need to comply.There is also the quality of the water that was used to clean out. Many private water supplies will have bacteria that can do this to a carcase. I have seen us having to put steralizing tablets into a bucket of water before cleaning down. All these places had private springs. J