it happened exactly same to me with civic 2008, but i kept ignoring, till i came to know, engine is not as good as it was earlier, i kept on filling water then i changed radiator, and t valve with original radiator cap, and it started behaving normal, u better bring it to honda, and let them diagnose, or change it all, including pipes, because once they are punctured, or has leakage, means other is also not good, because pressure developed inside, after changing these items, go for honda coolant, and specific one prescribed in your owners manual........