A leaky faucet can waste a surprising amount of both water and energy. Assuming the leak is about 10 drips per minute (slow drip), it can be estimated you are wasting around 3 liters of water per day. That’s about 350 gallons per year. As little as 10 drips per minute sounds, it really builds up over time.
In terms of energy, the average home uses about 5000 kilowatt hours of energy a year to heat water. An average household uses about 107,000 gallons of water per year. If you use 350 gallons of water per year on a leaky faucet, it can be assumed that the amount of hours is equal to its proportion in gallons. The percent of 107000 that is 350 is about 0.33 percent. It can be assumed now that 0.33 percent of 5000 kilowatt hours is how much energy is used. The answer is 165 kilowatt hours a year wasted on a leaky water faucet.