Saving energy around our homes is a good practice. We save not only money but also natural resources and the environment. For example, conservation of water can amount to considerable savings in your water bill. Let’s see how you can save water in your toilet tank. John’s dad replaced the old 3.5-gallon toilet with a 1.5-gallon tank in his house. There are four people in the family and each one used the toilet 5 times a day. How much money will John’s family save in a year? (3.5 – 1.5) ´ 4 ´ 5 ´ 365 = 14,600 gallons Let’s say the actual water bill from the Department of Water and Power (DWP) of Los Angeles shows that the water charge is \$1.70 per HCF and the sewage charge is \$2.30 per HCF. (HCF means one hundred cubic feet or 748 gallons of water) Savings in water = (14,600 / 748) ´ \$1.70 = \$33.20 Savings in sewage = (14,600 / 748) ´ \$2.30 = \$44.90 Total savings = \$33.20 + \$44.90   = \$78.10 John’s family will save about \$78 every year. The DWP is offering a water conservation rebate for replacing old toilet tanks. If the net cost of the tank is \$50 to John’s family, how long will it take to pay back for replacing the toilet? Estimate the answer: Less than 6 months Between 6 and 12 months Over 12 months