In short: replacing a standard showerhead with a WaterSense-labeled one saves the average family more than 2,700 gallons a year; replacing old, inefficient toilets saves about 13,000 gallons a year; and replacing old faucets and aerators saves about 700 gallons a year. Together with efficient appliances, a full retrofit saves the average family more than $380 a year. Enter your own fixtures above for a figure tailored to your home.
These are planning estimates from the flow rates and habits you enter. Your metered bill is the true measure of savings once the fixtures are installed.
How the savings are calculated
For each fixture, the difference between the current flow and the low-flow replacement is multiplied by how often it's used. Those per-fixture savings add up across the household, then scale to a dollar figure using your water rate:
water saved = Σ (current flow − new flow) × frequency × people
Monthly and yearly totals scale the daily figure by 30.44 days and 365 days. Dollar savings divide the gallons saved by 1,000 and multiply by your rate per 1,000 gallons.
Worked example. A three-person home switching an 8-minute, once-a-day shower from 2.5 to 2.0 GPM, five 1.6-gallon toilet flushes to 1.28 gallons, and four minutes of faucet use from 2.2 to 1.5 GPM saves about 25.2 gallons a day — roughly 9,198 gallons a year. At $9.00 per 1,000 gallons, that's about $82.78 saved a year.
Typical old vs. low-flow fixture rates
Standard rates reflect common federal maximums; low-flow rates are EPA WaterSense-labeled maximums. Annual savings are EPA's average-family figures for a full fixture swap, not the numbers from your own inputs above.
| Fixture | Standard | WaterSense low-flow | Typical annual savings |
|---|---|---|---|
| Showerhead | 2.5 GPM | 2.0 GPM or less | ~2,700 gal / ~$70 |
| Toilet | 1.6 GPF (pre-1994: 3.5–7) | 1.28 GPF | ~13,000 gal / ~$130 |
| Bathroom faucet | 2.2 GPM | 1.5 GPM or less | ~700 gal / year |
Source: U.S. EPA WaterSense, Statistics and Facts. Your own savings depend on your household size and habits — use the calculator above for a figure specific to you.
What else affects your savings
Hot water adds an energy line. Showers and faucets often run hot, so cutting their flow also lowers your water-heating bill. This calculator totals water and sewer cost only; if you want to estimate the energy side, use the energy to heat water calculator with your before-and-after flow rates.
Actual flow can differ from the rating. Water pressure, mineral buildup, and aerator wear all shift real-world flow away from a fixture's printed GPM or GPF. If you can, time how long it takes to fill a one-gallon container to check your current fixture's true flow before you buy a replacement.
A fixture that's already efficient shows zero. If you enter a "current" rate that's already at or below your "replacement" rate, that fixture contributes no savings to the total — there's nothing to gain from swapping it.
Household size scales the total. Per-fixture savings are calculated per person, then multiplied by the number of people you enter, since more people mean more showers, flushes and faucet minutes drawing on the same fixtures.
Frequently asked questions
How much water can low-flow fixtures actually save?
According to EPA WaterSense, swapping a standard showerhead for a WaterSense-labeled one saves the average family more than 2,700 gallons a year, replacing old, inefficient toilets saves about 13,000 gallons a year, and replacing old faucets and aerators saves about 700 gallons a year. Retrofitting a home with WaterSense fixtures and ENERGY STAR appliances saves the average family more than $380 a year overall.
Does this calculator include energy savings too?
No — this tool totals water and sewer costs only, using the rate you enter. Showers and faucets also use hot water, so cutting their flow lowers your water-heating energy bill as well; EPA WaterSense estimates a showerhead swap alone saves about $70 a year in combined water and energy costs for the average family.
What happens if my new fixture isn't actually lower flow?
If a replacement value is equal to or higher than the current value for a fixture, that fixture shows zero savings instead of a negative number — there's nothing to fix there, so check that field rather than trust the total.
Where do the default flow rates come from?
The current-fixture defaults reflect common federal standard flow rates: 2.5 GPM for showerheads, 1.6 gallons per flush for toilets installed since the early 1990s, and 2.2 GPM for bathroom faucets. The low-flow defaults are EPA WaterSense maximums: 2.0 GPM, 1.28 GPF and 1.5 GPM respectively. Change any of them, or use the preset dropdowns, to match your actual fixtures.
Does this include the cost of buying the new fixtures?
No, only the ongoing water and sewer savings from lower flow. Purchase and installation cost varies by fixture and whether you do it yourself, so weigh that against the annual savings shown here to estimate your own payback time.
Sources & references
- U.S. Environmental Protection Agency (EPA) WaterSense. Statistics and Facts.
- U.S. Environmental Protection Agency (EPA) WaterSense. Residential Toilets.
- U.S. Environmental Protection Agency (EPA) WaterSense. Bathroom Faucets.
Sarah Bennett, MS
Water Quality & Sustainability Specialist · Portland, Oregon
Environmental scientist (MS, Water Resources) with 9+ years in residential water quality, treatment, and usage efficiency, and 150+ completed assessments. Sarah writes and reviews the treatment, usage, and cost calculators on watercalculator.us. Read full bio
MS Environmental Science, Water Resources (2018) · BS Environmental Engineering (2016)