Plumbing – Water heater busted

It could be a loose fitting or the overpressure valve kicking in, but not likely.

The tanks in most water heaters eventually corrode, how fast depends on a number of factors, one of which is the amount and type of minerals in the water, as well as its acidity.

Once they do leak, repair is generally impractical and a new water heater is needed.

In any event, you need a plumber to check it out and solve the problem.

First off -- if your tank has been sitting idle eight months while full, there's a good chance that it's produced some hydrogen gas. To fix this, go up to the highest hot water faucet in the house and open it, but do not have any open flames or lit cigarettes present, and do not turn on any lights or appliances where the faucet is. If hydrogen is present, you will hear a hissing noise and/or see bubbles if you take a sample of the hot water with a glass. Keep the faucet open until the hissing stops and hot water flows steadily from the tap.

Second, "draining" a hot water heater is a misnomer -- your goal is to remove sediment from the heater, and that requires some oomph to push the sediment bits out. See this answer by BMitch for his suggestions as to flushing a typical residential tank like yours.

Finally, you may run into problems with stinky rotten egg smells in your hot water even after a flush -- hydrogen sulfide can also be a problem for idle hot water heaters, depending on your water supply and anode chemistry. Spiking the tank with hydrogen peroxide when you bring it back into service is a common, cheap solution to this problem -- a tee piece and valves can be used to provide a place to add it to the heater. There is more documentation on the peroxide fix available from Water Heater Rescue in case you want to try it, by the way. (Another trick for stinky heaters is an aluminum/zinc alloy or powered anode, but that doesn't always work if a heater is left idle for very long periods of time.)