So how much does a new toilet cost? Toilets start below $50 and go up from there. You can probably spend over $1,000 for a toilet if you really want to. Studies have shown, though, that there is little correlation between what a toilet costs and its flush performance. Therefore, a good quality toilet that will perform well can be purchased for as little as $75. If you choose to hire a plumber to install, the toilet installation will typically cost between $40 and $120.
Toilet CostBenefit Calculator
The savings you will achieve with a new toilet will depend primarily on the toilet that you are replacing. Obviously, if your old toilet uses 7 gallons per flush (gpf), you will get more water and wastewater savings than if your old toilet uses 3.5 gallons per flush. Since research has shown that the average flush volume of toilets in the U.S. is just about 3.5 gpf let’s use that as our baseline.
To calculate the benefits of installing a new toilet you need to know how much you pay for water and wastewater service. You can usually find this information on a copy of a recent water bill. It is also important to determine if you are billed in thousands of gallons (kgal) or hundreds of cubic feet (HCF). If you need to convert between HCF and kgal you can use these conversions:


 1 HCF (100 cubic feet) = 0.748 kgal = 748 gallons

 1 kgal (1000 gallons) = 1.34 HCF = 134 cubic feet

Please understand that the costs and savings calculated below are simple estimates. Your actual savings may be different. Also for the sake of simplicity we are not taking into account the time value of money as well as other standard elements of costbenefit analysis.
Step 1. Calculate Your Expected Annual Water Savings
Use the following equations to calculate your expected annual water savings. If you pay your water bill based on gallons usage – use equation 1A. If you pay your water bill based on cubic feet usage – use equation 1B.
1A. Savings in Gallons per Year
 # of people living in your house x 9.7 gallons/person/day x 365 days/year = Annual savings (gal.)
1B. Savings in Cubic Feet per Year
 # of people living in your house x 1.3 cubic feet/person/day x 365 days/year = Annual savings (cubic feet)
Step 2. Calculate Your Expected Annual Water and Wastewater Cost Savings
Using your annual savings and your local water rates, calculate your expected annual water and wastewater cost savings. If you pay your water bill based on gallons usage – use equation 2A. If you pay your water bill based on cubic feet usage – use equation 2B.
2A. Cost Savings (gallons)
 [Annual water savings (gal.) – From 1A / 1000] x [Cost of water per 1000 gal. + Cost of wastewater per 1000 gal.] = Annual water and wastewater cost savings
2B. Cost Savings (cubic feet)
 [Annual water savings (cubic feet) – From 1A / 100] x [Cost of water per 100 cubic feet (HCF) + Cost of wastewater per 100 cubic feet (HCF)] = Annual water and wastewater cost savings
Step 3. Calculate The Cost of Replacing All Your Old (pre1994) Toilets
Estimate the cost of purchasing a new toilet. If you are unsure about the likely cost of your toilet, use a value of $150. If you plan to use plumber to install your toilet use a cost of installation value of $120. If you plan to install the toilet yourself use a value of $15 for various materials.
3. Number of Toilets to Be Replaced x [Cost of new toilet + Cost of Installation] = Total Installed Cost
Step 4. Calculate the Payback Period
Calculate the amount of time (in years) it will take for the water and wastewater savings to pay for your new toilets. Remember that toilets have an expected product life of 20 years, so if the payback period is less than 20 years it is likely to be cost effective. A payback period less than 10 years would be excellent.
4. Total installed cost / Annual water and wastewater cost savings = Payback period (years).
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