To replace an electric hot water tank, disconnect the electricity, flush the plumbing, remove the existing tank, mount and fill the new tank, connect the wires, and restore the electricity. The required supplies include a circuit tester, masking tape, a marker and a hose. You also need an assistant.
Turn off the electrical supply at the circuit breaker box, and use a circuit tester to verify that there is no current in the tank wires. Fold a piece of masking tape around each wire, label it, and disconnect it.
Close the tank water supply valve. Open all of the household faucets until no hot water emerges. Keep the faucets open throughout the replacement procedure.
Connect a hose to the water tank drainage valve, place the other end of the hose in a sink, and open the valve. This drains the hot water out of the tank. Remove the hose, and disconnect the tank from the water lines. With help from an assistant, lift the tank off of its base, and replace it with the new tank.
Connect the new tank to the pipes, and open its water supply valve. Wait for the tank to fill, and then examine the open household faucets. Run hot water through the faucets for 60 seconds, and then shut them off. Connect the water tank wires, and restore the electrical supply.