Originally Posted by northernlad
What Revvy said, always keeping in mind the #'s 2, 3, 5 are not a designation of food contact safe.
While this is technically true, the numbers tell what type of plasitic you have and is not a designation of food safety by the FDA, if you know what the material is then you have a general idea of what is and what is not food contact safe. If you'll simply read up the the material in question.
here's a place to start http://en.wikipedia.org/wiki/Plastic_recycling
#2 HDPE: Water pipes, Hula-Hoop (children's game) rings, Milk, juice and water bottles; the occasional shampoo / toiletry bottle
most beer and or wine fermantation buckets are made of #2. Most brewers are leary of using any #2 that has any color other that white.
#3 PCV: Juice bottles; cling films; PVC piping
generally not considered safe for hot liqiuds but cold and cool is generally considered safe, many if not most cold water in home plumbing is PVC
#5 Polypropylene: Reusable microwaveable ware; kitchenware; yogurt containers; margarine tubs; microwaveable disposable take-away containers; disposable cups and plates
I'd say a cheap and easy way to tell if it will impart any off flavors are
1. If it smells, then wash it as see if it still smells.
2. if so let a solution of 1/4 cup Chlorox bleach per gallon of water sit in it a few days
3. let a bucket of water sit in it for a week if the water has an off flavors I would not use it