For your reference: I have just read a message from a Canadian friend. It quotes an article fromthe Financial Post of Canada about plastic food containers and says that those with NO. 3, or 6, or 7 in a trianagle under the bottle/container (or made of PVC, PS PC or Others ) ARE NOT SUITABLE for keeping food/water.
I can't say it is 100% ture or not but I would rather buy other No., or other matrial eg stainless steel.