It depends on the soil media you are using. If you're using a peat-based mix with a pH already in the 5's, it takes a LOT of irrigation with calcareous water (years) before the pH will move above neutral. I've never had an issue, despite watering with canal water laden with ca carbonate for many years.
If, with the aid of a decent pH meter (not test strips or bi-metal testers), you find that the pH is going above 7, you can throw a light sprinkling of sulfur on the top of your potted plants once a year.