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How we decide
Every verdict on this site comes from published rules and agency figures, checked on a stated date, run through the same household assumptions so the pages can be compared.
Updated 11 November 2026
Each page answers one decision: replace, fix, keep, skip or test first. The verdict is the answer for most US homes, and the "when the answer flips" list says which homes it does not fit. Behind both sit the sources below and a short set of assumptions, so a reader can check the work or redo it with their own numbers.
Where the facts come from
Fixture ratings and household savings come from EPA WaterSense for toilets, showerheads, faucets, irrigation controllers, leaks and hot water delivery, and from ENERGY STAR for dishwashers and clothes washers. Federal limits come from the Code of Federal Regulations as published on eCFR, with rule changes traced in the Federal Register. State limits come from each state's own statute or agency page. Rebates come from the water utility that runs them. Practical points on softeners, rain barrels and drip irrigation come from university extension services such as Penn State, Colorado State and Utah State.
WaterSense and ENERGY STAR are programmes run by the US EPA (ENERGY STAR jointly with DOE); this site is not affiliated with or endorsed by EPA.
Where two official pages disagree, the page says which figure it uses and why. EPA's toilet share of indoor use is one example: its older pages say nearly 30 percent, while its current chart says 24 percent, and we use the chart throughout.
How a verdict is reached
A verdict starts with the gallons: what the fixture you have uses, what a labeled replacement uses, and the difference over a year. It then checks the conditions that change the answer, such as household size, age of the fixture, local rules and whether the work is a homeowner job or a licensed pro's. Safety settles ties. Where a change involves gas, wiring or the main water line, the page says who should do it.
The verdict never depends on a price. A page gives the gallons and dollars of water saved each year; you set that against your own quote.
The household we assume
Unless a page says otherwise, the arithmetic uses the assumptions EPA publishes for its WaterSense calculator (How the WaterSense Calculator Works):
- 2.6 people in the household, the national average EPA uses.
- 5.05 toilet flushes per person per day, about 4,792 flushes a year for 2.6 people.
- Toilets at about 5 gallons a flush if installed before 1980, 3.5 from 1980 to 1994, and 1.6 after.
- $6.06 per 1,000 gallons for water and sewer together.
That last figure is EPA's assumption for its calculator, not a national average and not your rate. Wherever it appears, the page says so. Figures we multiply out ourselves are labeled "our arithmetic" and rounded, usually to the nearest ten gallons and the nearest dollar.
Dated checks and archived pages
Every source on the site was checked on 11 Nov 2026, and each source list says so line by line. Rebates, rules and agency pages change, so a page's date tells you how fresh its numbers are.
Some official pages have moved or gone offline. Several Department of Energy household pages are no longer published, and some state statute texts were not available to confirm on 11 Nov 2026. In those cases we use an archived copy (Internet Archive) and label it "archived copy of" its capture date. EPA's own January 2017 web snapshot is handled the same way: figures from it, such as the 70-gallon full bathtub, are called out as coming from that 2017 archive.
What we leave out
- Prices of fixtures, parts and labor. They vary too much by place and month to publish honestly.
- Brand rankings, star ratings and "best" lists. Labels and ratings come from EPA, ENERGY STAR and the test standards they cite.
- Tests we did not do. We have not flushed, timed or measured any product ourselves, and no page suggests otherwise.
- Figures we could not confirm from a primary source, such as plumbing-code pressure limits whose official text was not available to confirm on 11 Nov 2026. Those pages tell you to ask your plumber or code office instead.
How to apply your own rate
Find the water and sewer charges on your bill. If the rate is per 1,000 gallons, add the two together. If it is per hundred cubic feet (CCF), note that EPA equates 12,000 gallons with 16 CCF, so one CCF is about 750 gallons; divide the per-CCF rate by 0.75 to get a rate per 1,000 gallons.
Then take the page's gallons a year, divide by 1,000 and multiply by your rate. For example, if your combined rate were $10 per 1,000 gallons, the 10,640 gallons a year saved by replacing a 3.5 gpf toilet would be worth about $106 a year, against $64 at EPA's rate. Divide your installed quote by that figure for a payback in years.
Store links on some pages
Some pages link to one of four plumbing and water-treatment businesses run by the same team as this site; the about page names them. Each link sits in its own marked box with the sentence "run by the same team as this site" beside it, and it points to a page that lists parts or explains a job relevant to that decision. These links never change a verdict, a number or a ranking, and no page tells you to buy from them. Any store, or your plumber, can supply the same labeled products.
When the answer changes
When a source updates a figure, a rule takes effect or a rebate ends, the page is revised and its check date moves. If an agency publishes a newer study, such as the Water Research Foundation's 2026 end-use update, the page says which study each number comes from rather than mixing them.