I used rubber roofing material that I had left over from a job I did, I dont remember who made it, but it was one of the tire companies- so I would try a roofing supply house by you- I dont know if theyre all safe though- I lined a garbage can with it, filled it and put some feeders in for a couple of weeks, a bit of a pain in the neck, but I got around 750 gallons of liner for free