Brother, like you I also have just got my Civic 4 months ago. I mean first car with technology. My radiator reserve bottle was almost empty when I bought the car and my trusted mechanic (I have tried almost 10 guys before him - He is a rare gem among mechanics) put just tap water into it... He told me that the coolant comes with 50% distilled water and 50% concentrated coolant..
Although the car will run fine on water alone, but water is corrosive. And certainly not good for the radiator, as I have experienced on my Mehran.
Put plain water as a temporary fix and then visit 2,3 trusted and competent mechanics... 90 % of mechanics dont know what they are doing, go for those who have studied and got diploma or higher qualification in car repair. Get a price quote and ask about the complete procedure. I dont know much about Honda Service centre (I take my Civic to my mechanic), but I say get the radiator flushed as soon as possible.
