Topping up with Distilled water is a must for any Lead Acid Battery. It is to compensate the loss of liquid in the form of Gas (Hydrogen) from the cells while charging and Discharging / using. Check "atleast" once a week for the level of acid. If that is lower than the red mark, you need to top up. Otherwise no need. To avoid routine water addition, you can opt to replace the Lead Acid Battery with a Maintenance Free (Sealed) Battery. Best suit for domestic applications.