According to the Henderson-Hasselbalch equation, dilution of a buffer solution does not affect the pH of the solution, as long as the dilution does not change the ratio of the salt to acid (or base) concentration. However, if the volume of the buffer changes drastically, such as when large volumes of water are added to the buffer, the pH will tend to move towards 7, which is the pH of water. Diluting a buffer solution decreases its buffer capacity, which means that it becomes less effective at resisting changes in pH.