Our second night here the water stopped filling the tank in the toilet sometime in the middle of the night. I told the owners in the morning, and by the time they finally arrived in the evening (there was a big storm), we'd used it several times by filling the tank with water from one of the two sinks in the apartment. There was still water there, but it was hot water only.

Naturally, the moment she came, it was working again, and stayed working until this morning, when it stopped again. When she came, she told me at first I needed to be patient, that it filled slowly, but of course that wasn't the problem. And when I told her the hot water had still been working, but there was no cold, she said that was because it had been sitting in a warm tank. But the water was scalding hot, not lukewarm like when it's been warming in the sun. Anyway, once the toilet water came back, that situation went away.

The other odd thing is that the shower works normally when there's no water in the toilet and only hot water coming from the two sinks. You can change the temperature around.

The only thing I could possibly think is that they use a cistern for the hot water in the faucets and municipal water for the toilet and to mix with the faucets, and Mexico City has been in drought conditions. Could the city have cut off water to certain areas for conservation measures? But then what about the shower?