Since you appear to be in the USA, your power is more likely to be 240V rather than 220V. You can determine your actual voltage using a voltmeter at a wall plug. If you measure a standard outlet (120V) just double the value to get what the higher voltage is. If your voltage is actually 240V you will need less current to get the powers given in my previous post.
One option would be to use 3X 5500W @ 240V rated heating elements. These elements draw 23A each at rated voltage. This would give you about 16,500W of total power, and draw 69A of total current. The NEC says you shouldn't run continuous loads at more than 80% of the branch circuit rating, so that says your branch circuit needs a minimum rating of 69 / 0.8 = 86.25A. So, you would need a 90A (closest standard circuit breaker) branch circuit, wired with 2AWG or 3AWG (depending on temp rating of wire insulation) copper - which is expensive. There are no plugs available for higher than 60A, so you would need to have everything hard wired from the service panel to the control panel. Since the control panel will be hard wired to the structure wiring, it will have to pass electrical inspection (if you skip this part, and burn something down, your insurance company will probably refuse to pay.)
16,500W is 16,500 / 0.293 = 56,300 BTU/hr, so that would be enough to heat your water in 1 hr, if you had no heat loss from your vessel. Insulating the bottom and sides of the vessel, and covering with an insulated lid, will minimize heat loss during heating, and should get you close to your 1 hr heating target.
Brew on