Toilet Water Use & Replacement Savings Calculator

How much water does your toilet use, and what might a lower-GPF replacement save? Compare your household’s flushing, usage rates and entered replacement costs.

Current & proposed toilets

Editable example; use your fixture’s actual GPF.

Use the proposed fixture’s specification.

Don't know your toilet's GPF?

Look for a gallons-per-flush marking on the toilet or manufacturer information. It may say GPF or gal/flush. If no reliable marking or specification is available, enter your own best-known value. Age alone does not determine GPF. No age, brand or model lookup is used; casual tank dimensions or refill volume are not treated as measured flush volume.

Household

Positive whole number.

Decimals or zero are allowed for averages.

Changes project cost, not household flushing.

Annual use always uses 365 days.

Optional replacement costs

Enter your purchase price; blank costs are omitted.

Enter your installation estimate; blank costs are omitted.

Water + sewer usage rate

Blank means unknown, not free. Use the marginal/usage rate.

Optional

Find My Water/Sewer Rate

Use your utility bill to estimate the variable rate affected by water savings.

Enter the rate directly in the main box; the helper is optional.

How to read your bill

Look for variable usage, consumption or volume charges for the same period as the water usage. Exclude fixed monthly/base/service charges; those generally do not disappear when water use falls. Utility bill structures vary. CCF means hundred cubic feet; 1 CCF is approximately 748 US gallons (calculations use 748.052). For tiered utilities, the relevant marginal rate for gallons you expect to save is generally the best planning input. This helper does not model tier schedules.

How it works

People × average flushes per person gives household flushes per day. Multiply by current or proposed gallons per flush, then by your selected days for a month or 365 for a year. Toilets replaced changes replacement cost, not flushing. All modeled household flushes are assumed to occur on toilets represented by this GPF comparison.

Variable water/sewer cost uses your rate per 1,000 gallons or per CCF. Savings are current minus proposed. Entered project cost is (price per toilet + installation per toilet) × toilets replaced. Simple payback divides that cost by positive annual savings, using unrounded values.

Understanding the estimate

This is a water-use and variable operating-cost estimate, not a recommendation to replace a toilet. Actual flushing behavior and consumption vary with fixture condition, adjustments, dual-flush use and other factors. GPF examples are not an age-based prediction. Fixed utility charges generally do not disappear when water consumption falls; water savings do not guarantee equal bill savings.

Project cost includes only entered purchase and installation amounts. Parts, disposal, permits or other unentered costs can change the result. Blank cost components are omitted; a partial entered project cost is not a complete quote. No rebates, brand recommendations, plumbing-code compliance advice or tiered billing model are supplied.