The simple combination of water and vinegar has been used to clean hardwood floors for many years. Often I hear "It's what my grandma used". Most would agree that it really does clean your floor. The more important question is whether it is good for your floor. Does it do any harm? . . .
First of all, it is important to note that cleaning a hardwood floor means cleaning the finish - or topcoat - that was applied to the floor when it was installed. Second, white vinegar is acidic in nature. It has a PH factor of about 2.5. That means that it is quite acidic since the neutral number between acidic and alkaline is 7 (lower numbers being more acidic and higher numbers more alkaline). As a result, the regular application of vinegar to a hardwood floor can break down the finish over time.
In addition, the water - in vinegar and water - can be a problem. Contrary to what some might think, the finish on your hardwood floor is not waterproof. The finish is water resistant meaning that moisture can penetrate and get into the wood itself. Over time, a condition called "crowning" (see image below) may develop. In this case, moisture seeps into the surface of the floor causing the top side of the boards to swell or expand. This forces the middle of the boards to rise above the edges. Crowning is the opposite of "cupping" which happens when moisture enters the wood from the bottom side.
So what is the best way to clean your hardwood floor? My favorite is Bona cleaner. This cleaner contains no harsh chemicals, has no smell and takes only minutes. First, dust or sweep to remove loose dirt, dust, sand, etc. next, spray a light mist of cleaner over a small section of the floor and wipe with a microfiber pad. That's it!