I've become an expert on water. Unfortunately, that's due to ongoing health problems.
Here are some good guidelines to follow:
1) Test your water's pH. Our tap water is 6.0, which is acidic/BAD. You want your water to be as close to your blood's pH as possible. Your blood has to maintain a 7.4 pH, or it starts leaching from your bones, etc to get to that 7.4 number. If your water is not close to 7.4, you might want to consider drinking bottled water, but test it, or ask the supplier first. No sense in drinking bottled tap water.
2) Reverse osmosis systems are good, but they remove all the minerals, etc out of your water, so will actually make your water MORE acidic. One reverse osmosis system engineer told me that reverse osmosis water can be as acidic as 4.0. So if you have an RO system, make sure you add the proper alkaline minerals back in.
3) You "should" drink half your body weight in water every day. In other words, if you weigh 160lbs, you should try to drink 4 20-ounce glasses of water per day; if you weigh 120lbs, you only need to drink 3 20-ounce glasses of water per day.
4) Avoid drinking large amounts of water with meals. A lot of diets advocate that you drink a large glass of water before a meal. However, water dilutes the stomach's hydrochloric acid, and drinking water right before a meal reduces your body's ability to digest your food. Digesting your food properly is very important. Failure to do so causes all kinds of problems, and leads to chronic illnesses.
Hope that helps someone.