Water Savings From Toilet Replacement Calculator

Existing Average Toilet Flush Volume (gpf):

gpf: gallons per flush

Replacement Flush Volume (gpf): gpf

Toilet Use per Person per Day: times

# of Occupants: people

Days per Year: days

Cost per Gallon:

1. What is Water Savings From Toilet Replacement Calculator?

Definition: This calculator estimates the annual water savings (gallons per year) and money saved from replacing old toilets with WaterSense-labeled models, based on flush volume differences, usage patterns, and water cost.

Purpose: It is used to assess the water efficiency and financial benefits of toilet upgrades, supporting conservation efforts and cost savings in residential or commercial settings.

2. How Does the Calculator Work?

The calculator uses the following formulas:

Water Savings Formula:

$ \text{Gallons Saved per Year} = (E - R) \times U \times O \times D $

Where:

$ E $: Existing Average Toilet Flush Volume (gpf)
$ R $: Replacement Flush Volume (gpf)
$ U $: Toilet Use per Person per Day (times)
$ O $: # of Occupants (people)
$ D $: Days per Year (days)

Money Savings Formula:

$ \text{Money Saved per Year} = \text{Gallons Saved per Year} \times \text{Cost per Gallon} $

Where:

$ \text{Cost per Gallon} $: Price of water (dollars/gallon or cents/gallon)

Steps:

Select the existing flush volume based on installation date or enter a custom value.
Enter the replacement flush volume (typically 1.28 gpf for WaterSense models).
Enter the daily toilet use per person, number of occupants, days per year, and cost per gallon.
Calculate the water savings and money saved using the formulas.
Display the results in gallons and dollars per year with 2 decimal places.

3. Importance of Water Savings Calculation

Calculating water and money savings is crucial for:

Water Conservation: Reducing household or commercial water usage to promote sustainability.
Cost Savings: Lowering water bills through efficient toilet replacements.
Compliance: Meeting regulations like the Energy Policy Act (EPAct) of 1992, which limits flush volumes to 1.6 gpf post-1994.

4. Using the Calculator

Example 1: Replacing a 3.5 gpf toilet (1977-1994) with 1.28 gpf, 5 uses/day, 4 occupants, 365 days, $0.005/gal:

Existing Flush Volume ($ E $): 3.5 gpf
Replacement Flush Volume ($ R $): 1.28 gpf
Toilet Use ($ U $): 5 times/day
Occupants ($ O $): 4 people
Days ($ D $): 365 days
Cost per Gallon: $0.005/gal
Gallons Saved: $ (3.5 - 1.28) \times 5 \times 4 \times 365 \approx 13,316.00 $ gallons
Money Saved: $ 13,316.00 \times 0.005 \approx 66.58 $ dollars
Result: $ 13,316.00 $ gallons/year, $ 66.58 $ dollars/year

Example 2: Replacing a 5.0 gpf toilet (before 1977) with 1.28 gpf, 6 uses/day, 2 occupants, 365 days, $0.01/gal:

Existing Flush Volume ($ E $): 5.0 gpf
Replacement Flush Volume ($ R $): 1.28 gpf
Toilet Use ($ U $): 6 times/day
Occupants ($ O $): 2 people
Days ($ D $): 365 days
Cost per Gallon: $0.01/gal
Gallons Saved: $ (5.0 - 1.28) \times 6 \times 2 \times 365 \approx 16,614.80 $ gallons
Money Saved: $ 16,614.80 \times 0.01 \approx 166.15 $ dollars
Result: $ 16,614.80 $ gallons/year, $ 166.15 $ dollars/year

Example 3: Replacing a 1.6 gpf toilet (1994-Present) with 1.28 gpf, 4 uses/day, 3 occupants, 365 days, $0.0075/gal:

Existing Flush Volume ($ E $): 1.6 gpf
Replacement Flush Volume ($ R $): 1.28 gpf
Toilet Use ($ U $): 4 times/day
Occupants ($ O $): 3 people
Days ($ D $): 365 days
Cost per Gallon: $0.0075/gal
Gallons Saved: $ (1.6 - 1.28) \times 4 \times 3 \times 365 \approx 1,314.00 $ gallons
Money Saved: $ 1,314.00 \times 0.0075 \approx 9.86 $ dollars
Result: $ 1,314.00 $ gallons/year, $ 9.86 $ dollars/year

5. Frequently Asked Questions (FAQ)

Q: What is gpf?
A: gpf (gallons per flush) measures the water volume used per toilet flush, regulated by standards like the EPAct of 1992.

Q: Why replace older toilets?
A: Older toilets (3.5 gpf or 5.0 gpf) use more water than modern WaterSense models (1.28 gpf), leading to significant savings.

Q: How is the cost per gallon determined?
A: Check your local water bill for the rate, typically provided in dollars per gallon or cents per 100 gallons, and convert as needed.