By JAY COLEMANThe San Francisco Public Utilities Commission on Monday said it has shut down the city’s water heater systems after a water heater in a building in the city went out overnight.

The utility, which runs San Francisco’s electrical grid, said it was unable to provide power to about 500 customers because of the problem, but it said that many of them could be connected to water lines that were already operational.

In a statement, the utility said it shut down power to nearly 1,400 customers and that it was investigating the cause of the outage.

It said that, as of 6 p.m., there was no evidence of a cause and no indication of an imminent threat to the city.

It also said that customers could connect to water meters in other cities and that the utility was monitoring the situation closely.

The company also said it is working with the utility to improve the maintenance and service of its water heater system.

It is not the first time water heater waterlines have gone out in San Fran’ s power grid.

In May, about a dozen water heater units in the Mission District went out after water pipes in the building leaked, causing a transformer to blow out.

The city has been dealing with a major power outage since November when a transformer went out, causing major damage to the utility’s electric grid.