Water Savings Calculator

Estimate water saved by a low-flow fixture.

Old flow rate

gpm

New flow rate

gpm

Minutes of use per day

min

Water cost per gallon(optional)

Includes water + sewer

Results update as you type.

Water saved per year

—

Money saved per year—

How it works

Switching to a low-flow showerhead, faucet, or other fixture cuts water use, and this calculator estimates how much water and money you save. You enter the old and new flow rates in gallons per minute (GPM), how many minutes the fixture is used per day, and the cost per gallon of water, and it returns the gallons and dollars saved per year. The calculation multiplies the reduction in flow rate by the daily minutes of use to get daily savings, then scales to a year and applies the water cost. Low-flow fixtures can meaningfully reduce consumption: a standard showerhead might use 2.5 GPM while a low-flow model uses 1.5 GPM or less, saving a gallon every minute. Over a year of daily showers, that adds up to thousands of gallons and real money, especially since the water cost should include both water supply and sewer charges, which together are often higher than people realize. Beyond the direct savings, using less hot water also cuts the energy to heat it, so the true savings are often larger than water alone. Reducing water use also benefits the environment by conserving a precious resource and lowering the energy used to treat and pump water. Enter the old and new flow rates, daily use, and water cost to estimate your savings.

Formula

Gallons saved = (old GPM − new GPM) × minutes/day × 365

The water saved per day is the reduction in flow rate (old minus new gallons per minute) times the minutes of daily use. Multiplying by 365 gives the annual water saved, and multiplying that by the cost per gallon gives the money saved each year.

Source:Water conservation

We review all our tools from time to time to ensure accuracy.

Worked example

Old flow rate:2.5New flow rate:1.5Minutes of use per day:10Water cost per gallon:0.015

(2.5 − 1.5) × 10 × 365 = 3,650 gal/year saved, about $54.75 a year.

How to use this calculator

1
Enter your values
Enter old flow rate, new flow rate and minutes of use per day.
2
Adjust the options
Adjust water cost per gallon if they apply — sensible defaults are already set.
3
Read your result
Water saved per year updates instantly as you type — no button to press.

Frequently asked questions

How much water can a low-flow fixture save?

It depends on the flow reduction and use. Cutting from 2.5 to 1.5 gallons per minute saves one gallon every minute of use. Over 10 minutes a day for a year, that is 3,650 gallons. Multiply the flow reduction by daily minutes and 365 to find the annual savings, which this calculator computes.

What flow rate is considered low-flow?

For showerheads, standard is around 2.5 gallons per minute, while low-flow models use 2.0 or less, often 1.5 GPM. Low-flow faucets are typically 1.5 GPM or below versus 2.2 for standard. WaterSense-labeled fixtures meet efficiency standards. Lower flow rates save more water, though very low rates can affect performance, so many models maintain pressure while reducing flow.

Should I include sewer costs in the water price?

Yes. Water bills usually charge for both water supplied and sewer service, and sewer charges are often based on water use. Together they can significantly exceed the cost of water alone, so including both gives a truer cost per gallon and a more accurate estimate of the money you save by reducing water use.

Do low-flow fixtures also save energy?

Yes, when the water is heated. Using less hot water in showers and faucets reduces the energy your water heater consumes, so switching to low-flow saves on both the water bill and the energy bill. This calculator estimates the water and its cost; the added energy savings mean your total savings are often larger than shown.

Is the water savings worth the cost of new fixtures?

Usually yes. Low-flow showerheads and faucet aerators are inexpensive, often paying for themselves within months through water and energy savings, then saving money every year after. Larger fixtures like efficient toilets cost more but still pay back over time. Use the annual savings from this calculator against the fixture's price to estimate the payback period.