Yes. A few drops of water from a leaking pipe may not do any permanent damage to the system, but the moisture can become trapped inside the backup media and destroy it. Also exposure to direct sunlight may not affect the system at all, but can warp a backup tape.
Probably the largest threats to magnetic storage media are strong magnetic fields. This is another reason why storing tapes next to a computer monitor, TV monitor, stereo or even household electrical appliances like refrigerators is not a good idea.