I got some 25 litre used barrels from a car wash, i rinsed them once but they still stink of the flammable liquid or glass they had in them before in the car wash. I had pure water put in, will they be ok to use for cleaning? Also, a TDS meter won't register these chemicals will it? It just measures the water itself, right? Also where can i buy some barrels, went to B and Q but they didnt have them!