A low level of electrolyte fluid will cause the battery to discharge quickly.

Inspect the electrolyte level at least once a week. If it is low, remove the caps and add enough distilled water to bring the level between the upper and lower level (illustration).
Do not overfill.
Examine the specific gravity of the electrolyte with a hydrometer, especially during cold weather. If it is low, recharge the battery.
Battery Maintenance
Battery RechargingMazda 6 Owners Manual: Operating the Power Windows
NOTE
Each passenger window can be operated with each door switch when the
power window lock switch on the driver's door is in the unlocked position.
Each passenger window can also be operated using the master control switches
on the driver's door.
Normal opening/closing
To open the ...
Mazda 6 Owners Manual: Rear washer hose removal/installation
1. Disconnect the negative battery cable.
2. Remove the washer tank. (See WASHER TANK REMOVAL/INSTALLATION)
3. Partially peel off the right side mud guard.
4. Remove rear washer hose No.1 from the clips.
5. Remove rear washer hose No.1 and joint pipe A.
6. Remove the A-pillar trim. (See A-PIL ...