How These Pages Are Made
Every figure on Tank & Tankless comes from a federal source or a maker document that was opened and read, and each page shows the date it was last checked.
Sources we rely on
The pages draw on primary sources. For efficiency, savings and lifespans, that means the U.S. Department of Energy, including its Energy Saver pages. Those pages no longer load on energy.gov, so the guides link archived copies and label them as such. ENERGY STAR supplies product criteria and savings estimates. Federal efficiency rules come from the Federal Register and the eCFR, tax credits from the IRS, energy prices from the EIA, and water hardness from USGS. Scalding and Legionella guidance comes from CPSC and CDC.
For installation, care and fixes, the guides use maker manuals and spec sheets from companies such as A. O. Smith, Rheem, Rinnai, Navien and Noritz, plus extension services and city building bulletins as code examples.
How numbers are checked
Each number is taken from the source itself, not from a summary or search snippet, and each page cites the sources behind its figures. When sources disagree, the page names which one it follows. For example, it gives DOE's tank lifespan range rather than mixing several. Figures we calculated ourselves, such as a cost at a given energy price, are labeled as derived and show the inputs. Every page shows the month its sources were last checked.
How costs are handled
Costs come from federal figures and maker data: DOE's rulemaking averages, ENERGY STAR estimates, FTC EnergyGuide label ranges and EIA energy prices. When ENERGY STAR reports an informal contractor survey, the page says so. No contractor quotes are used, and local prices can differ widely from national averages.
What we leave out
There are no brand rankings, "best of" lists or star ratings. Product tests are not claimed, because none are run. Forum anecdotes are used only to learn which questions people ask, never as evidence. Code section numbers are not quoted unless the code text itself could be checked.
Corrections
Pages are revised when a source changes or a mistake turns up. Errors found in later checks are corrected, and the revised date at the top of the page changes. Ownership and store links are explained on ownership and store links, and the site itself is described on the about page.