The water heater in my house succumbed to old age and stopped functioning.
There was no tell tale sign at all.... Initially, it was kinda half dead. It managed to spill some warmth if we run the shower long enough at a slow rate. The next day, it totally gave up and we were left stranded in the toilet screaming.
Best la... We have to now boil hot water to pom pom till a new one is installed.