Purchase pH test strips if you have not done so already. You can find these strips at any local pet store, as people who own fish use them to test a fish tank's pH. You may notice several different types of pH strips being sold, but you're looking for the simple variety that have only one color indicator on them. If you have trouble, just ask the associate for pH strips to test alkaline water.
Turn your faucet on, and fill a clean glass with water. If you use a glass that's dirty or wasn't completely rinsed after you washed it, residue and debris could affect the pH reading. If you're uncertain about how clean the glass is, wash it thoroughly with soap, rinse it completely and allow it to dry a few minutes before you fill it with water.
Place a pH test strip into the water and hold it there for up to 30 seconds, or until the color on the indicator stops changing. Remove the test strip and compare the color on it to the key you received with the strips. If the pH reading it significantly greater (basic) or less (acidic) than seven (neutral), your water's pH is off.