Lee's Pond Tubing is the best. It comes in clear if you want that, or black (which I prefer for tank plumbing). It's very thick and kink-resistant. Most LFS should have it, or can get it, it is sold by the 50' or 100' box and stores typically sell it by the foot. Always buy more than you think you will need. Stinks to have to go back and buy a longer piece.
For tubing/piping for potable water - it should all be lead-free now, there was a new law passed early in 2014 so that all plumbing parts like fittings, faucets, pipe and tubing be lead-free.
Not sure if the pond tubing falls into that category but the Lee's is vinyl. I've used it for many years and it stands the test of time.
Jenn