Radiator

All radiators have two sets of hoses, Which hose is leaking on your vehicle?.. it might not even be the hose and more over could be that the hose clamp/ring simply needs to be tightened. If left untreated/corrected your coolant system can lose pressure thus reducing the engines efficiency. Typically, one would need to replace their belts and hose every 4 years, but inspecting them within those 4 years is critical.

Follow Up: It's probably a good idea that if you're going to replace the hoses.. to replace the thermostat also.