failing constant

The problem with occasionally finding a good deal on coffee and buying four bags is that I then get used to there being a spare bag somewhere in a cupboard and thus forget when I get to the bottom of the tub when there is no spare bag. Frequently there's just sufficient in the tub for a full load but this morning there was only enough to fill up to the "2" line, resulting in a half-filled flask of slightly weak-tasting coffee, which lost its heat noticeably more quickly throughout the day.