Never ever use faucet water or drinking water to clean a monitor, especially LCD monitors. Also, never ever buy LCD cleaners, complete rip-offs.
There's a nice mixture which you can prepare on your own: 70% isopropyl alcohol (can be purchased from any hypermarket, usually found in the lens cleaning supplies isle) and distilled water. I found that a mixture of 60% alcohol and 40% distilled water is the best. also, use a microfiber based dusting cloth to clean the screen prior to applying the solution. This also works in cleaning anything with an optical lens, from high def cameras to endoscopes.
[Edit] Distilled water can be acquired from an
air conditioner [/Edit]