Water temp is inconsistent on all the faucets in the house. Started when I turned the water off on the hot water heater to try to teach my daughter about conserving water when she showers (We live in So. CA). I only turned it off for a couple of minutes.

Do you have a hot water circulation pump ?

Try to go to the most distant faucet in your hose, turn hot water ON and let it run for 15 minutes. Than, see if the water temperature remains constant of if it continues to fluctuate

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Milo