For The Basement Watchdog battery backup systems powered by a wet-cell battery, water should be added to the battery every 4-6 months, although as the battery ages this fill time may be shortened. If the battery is running low on water every few weeks, it may be time to retire that battery and replace it. You can get your battery load-tested at your local automobile service station.  If the battery tests fine, your system may be overcharging the battery, which means your backup system may need to be sent to Glentronics for service.