philo* wrote:

She said the water heater is new, so it should not be dirty yet.

New is relative - in a dirty environment it doesn't take very long for the
honeycomb filter to get dirty.

OTOH, I just realized there is something fishy about this story...
I don't think they even make water heaters with pilot lights any more.

Pilots for gas water heaters are still quite common. It's not an energy loss
situation (like an oven range) because the heat from the pilot still goes into
the water.