If you're the original owner, and the factory fill extended life coolant is what's currently in your cooling system, you should NOT need to go to the trouble of chemically flushing. Honda uses a very good antifreeze at the factory that's ideally chemically compatible with aluminum and Honda's gasket materials. The generally available flushes aren't that effective and unless TOTALLY flushed with disitlled water, may affect the working life of the replacement antifreeze solution. The more vigorous chemical flushes that shops use may have unwanted long-term affects on various gasket materials if mishandled. Peruse your owner's manual - it should tell you all you need to know in the do-it-yourself maintenance section about the proper procedures. When you drain it, the appearance will tell everything. Honda uses a green coolant - chemically equivalent to the well-regarded Toyota "pink". If it drains clear green (no cloudiness), and looking through the radiator fill hole shows only bright metal in the core tubing (no deposits), you're good to go with a few distilled water* flushes with warm-up sessions between each at idle until the effluent drains water-white, and refill with whatever antifreeze you wish. Honda extended life antifreeze concentrate can be hard to find at Honda auto dealers - often what they sell is 50% premix. (After you drain, even if you go to the trouble and mess of removing the engine block drain plug(s)**, there will be some flush water leftover inside which will affect the final concentration if you use premix.) Someone posted a year ago that he found the Honda extended life concentrate at Honda motorcycle dealers - same chemistry since Honda liquid-cooled bike motors are aluminum, too. I don't doubt you could use Toyota "pink" or Nissan "green" extended life antifreeze, too. All are ethylene glycol-based, with OAT long-term corrosion inhibitor, and a stiff dose of phosphate for quick aluminum protection. The dye color is the chief difference.
*Distilled or "de-ionized" water (same thing essentially, just different ways of getting to the final product) is as good as it gets for diluting to 50% final concentration - you're right to be concerned about tap water. Even the softest tap water will have some mineral content.
**Be VERY careful here if you elect to remove the engine block drain plug(s). They're steel and they're screwed into aluminum. Stripping the soft aluminum threads by over-torquing or x-threading is a wonderful way to ruin your day.
