Web alarm clock for 6:18 a.m.
As you hand over the water-filling duty at 6:18 am, set this alarm so the next person remembers to fill the buckets before the pressure drops. The alert leaves enough time to check the containers and finish the task before 7:00 am, without relying on a hurried reminder passed across the doorway.
Because the buckets depend on someone else hearing the cue, test the alarm sound now, while you are both present. Set it for a minute or two ahead, raise the volume to a level that carries over running water, and confirm that the tone is clear. Then reset it for 6:18 am. Keep the browser active and the phone awake: if either is shut down, the alarm may not sound, and the buckets could remain empty when the pressure weakens.
If the person taking over still has to travel, include the early-morning journey in the handover. Jeepney waits and changing traffic near schools or markets can stretch a short route even before 7:00 am. Check their likely arrival time and place the alarm early enough for them to reach the tap, gather the buckets, and start filling rather than hearing it while still on the road.