If your water heater runs on electricity, then you can expect it to use a lot of power while in use. A typical water heater uses 3kWh of electricity every hour. However, water heaters only run up to 3 to 4 hours per day in most cases. That means you end up using up to 4000 to 5000 watts of power. So in your electricity bill, your water heater uses up a considerable chunk. To save up on the cost of using an electric-run water heater, consider investing in solar heaters.