Some garden hoses leach lead and other chemicals into the water. The problem is that they are made of PVC, which uses lead as a stabilizer.
Consumer Reports tested 16 brands of garden hose sold at national chains and on the internet. In some hoses they measured 10 to 100 times more lead than the EPA considers safe coming out of a faucet. The hoses they found to be lead-free are: Swan Marine/Camper Hose, Teknor Apex Boat & Camper Self-Straightening Hose and the Better Homes and Gardens Kink-Free Hose.
See also this lead-free eco garden hose available from Amazon.