I would like to try to may my own sump for pool pond. I'm adding up my cart it is an awful lot all the things i need. The main piece I need being the 55 gallon drum is a good $150 for a new food grade one. We have a ton of them at work and I could take one for free. They probably had some really nasty stuff in them though. I have a good pressure washer do you think if I cleaned it out good it would be safe to make my sump?