Water Heater Leaking At Top

water heater
An appliance for supplying hot water for purposes other than space heating or pool heating.
a heater and storage tank to supply heated water
Water heating is a thermodynamic process using an energy source to heat water above its initial temperature. Typical domestic uses of hot water are for cooking, cleaning, bathing, and space heating. In industry, both hot water and water heated to steam have many uses.

leaking
(of a container or covering) Accidentally lose or admit contents, esp. liquid or gas, through a hole or crack
(of liquid, gas, etc.) Pass in or out through a hole or crack in such a way
(of secret information) Become known
(leak) an accidental hole that allows something (fluid or light etc.) to enter or escape; "one of the tires developed a leak"
(leak) soft watery rot in fruits and vegetables caused by fungi
(leak) tell anonymously; "The news were leaked to the paper"

top
Exceed (an amount, level, or number); be more than
top(a): situated at the top or highest position; "the top shelf"
the upper part of anything; "the mower cuts off the tops of the grass"; "the title should be written at the top of the first page"
Be at the highest place or rank in (a list, poll, chart, or league)
Be taller than
exceed: be superior or better than some standard; "She exceeded our expectations"; "She topped her performance of last year"