I have a 50 gal plastic barrel that I fill 2/3 with water, to use in case of a water outage. I would like to keep it from freezing this winter (it's in my garage, which isn't insulated). I bought a vat of insulation to wrap around the barrel but someone told me that wouldn't keep it from freezing. So I just bought some heat tape (I think it's called), but the salesperson told me it might melt the plastic because it get pretty hot. If I wrapped the insulation around the the barrel, then wrapped the heat tape around the insulation would that work to keep the water from freezing or would it create a fire hazard?