Instead of running the bathroom faucet until the water becomes hot enough to shave, consider this alternative: Fill a glass measuring cup with water and zap it in the microwave for a minute or so. Then, use this hot water to rinse your razor while you shave. You'll likely save between 2 and 10 gallons of hot water per shave, depending on your faucet-use habits. Taking into account the cost of the water as well as the cost to heat the water, this could mean a utility bill savings of up to $50 per year-more than twice as much as the average U.S. male spends on shaving supplies annually.
On the other hand, the cost of running a microwave for two minutes a day is a little over a buck per year.
If all of the 68 million men in the U.S. who shave with a blade and razor saved 1 gallon of hot water per shave, the annual savings across the country would be nearly 19.6 billion gallons of water, and roughly $300 million in utility costs-enough to buy 176,000 Energy-Star-qualified flat screen TVs.
Sources:
California Urban Water Conservation Council