Suppose you move into a new house and need to purchase a washing machine. You’ve heard that the new front-loading machines use less water, but that they are more expensive. A traditional washing machine costs $300, whereas the water-efficient washing machine costs $900. So how do you choose?

If the average family washes 300 loads of laundry per year, and traditional washing machines use 100 L more water per load than water-efficient machines, how many liters would an efficient washing machine save per year?

300 loads/year × 100 L/load = 30,000 L/year

If the average cost of water in the United States is $0.50 for every 1,000 L, how much money would you save annually by using the more efficient washing machine?

30,000 L/year × $0.50/1,000 L = $15/year

Given your calculated annual savings, how many years would it take for your water savings to pay for the more expensive, high-efficiency washer?

($900 – $300) ÷ $15/year = 40 years

Your Turn If the average cost of water in the United States doubled to $1.00 for every 1,000 L, how much money would you save annually by using the more efficient washing machine and how many years would it take to pay for the more expensive, high-efficiency washer?