I have a 2001 Chevy Blazer which I notice a water drip from behind the passenger side wheel well. I notice this drip coming from the underside and is located somewhere behind the wheel well. I have examined the hoses and reservoir and they seem to be in good shape. The carpets are dry inside the car and no evidence of any leaks. The radiator needs to be topped off about twice a week and when topped off the reservoir is empty. I have attached a photo showing general location where I see the drip. Could it be a leak somewhere in the heater core?

 

That water drip is probably normal condensation from the A/C system if the water is clear. If it is colored green or what ever color the coolant is, then you have a heater hose or other leak in the cooling system.