Hard Water Map & Water Quality Statistics (2026)

Publisher / creator: Water System Guide (https://watersystemguide.com) Version: 1.0.0. Data verified: 2026-10-11. Package built: 2026-10-21 Companion page: https://watersystemguide.com/guides/hard-water-statistics/ DOI: 10.5281/zenodo.23534609 (Zenodo) License: CC BY 4.0 for the compilation. See LICENSE for third-party figures.

What this is

This dataset has 160 US and global water statistics. Each one is quoted exactly as it appears on the companion page and in the CSV published on watersystemguide.com (/data/hard-water-statistics-2026.csv). Every row links to the primary publisher. Water System Guide is an independent research publisher. It is not a manufacturer, dealer, installer, utility or laboratory.

The 12 topics are hardness, hardness prevalence, softener adoption, public water systems, lead service lines, PFAS, private wells, chloride regulation, salt use, appliances, consumer concern and global access.

Files in this package

path	what it is
data/data.csv	160 rows, one statistic per row, 16 columns (identical to data.csv in the Zenodo record)
data/data.json	The same 160 records in JSON with title, version, license and source page (identical to data.json on Zenodo)
README.md	This file
LICENSE	CC BY 4.0 for the compilation, plus notes on third-party figures (identical to Zenodo)
METHODS.md	Source selection and verification steps
DATA-DICTIONARY.md	Column types for data/data.csv
CITATION.cff	Machine-readable citation
summarize.py	Prints row counts by topic, source type, license note and year. Standard library only: python3 summarize.py

The canonical record is the Zenodo DOI. This SourceForge copy is a mirror of the same data files.

Methodology

1. Primary sources only. Figures come from the body that produced them. That means federal agencies (EPA, USGS, CDC), state agencies, utilities, universities, WHO/UNICEF, original survey publishers (Gallup, WQA) or the foundation that commissioned a study (WQRF/Battelle). Roundup blogs and vendor pages were not used.
2. Checked against the live source. On 2026-10-11, each of the 64 source URLs was fetched. HTML and PDF files were converted to text, and the exact wording or table value was matched for every statistic. The research ledger records the quote, the source date, the retrieval date and the HTTP status. One CDC page blocks automated requests, so it was read with a browser-style reader.
3. Dated, not blended. Each statistic keeps its own date. Revised series stay as separate dated rows. For example, EPA's lead service line estimate is listed as 9.2M (2023), 9M (2024) and 4M (2025).
4. Excluded. Figures that could not be traced to a primary source were left out. This includes "85% of US homes have hard water" and market-size figures that only appear in paywalled press releases.
5. Unit conversions done by Water System Guide are labelled as ours on the companion page.

Columns

column	meaning
id	Stable row ID, matching the website CSV
topic	Machine-friendly topic slug
section	Section heading on the companion page
statistic	The statistic, worded exactly as published
geography	Area the figure covers. Water System Guide assigned this from the source and wording
year	First year in source_date, which is the publication or data year
source_date	Source publication or data date, as recorded in the ledger
source_name	Publishing organization
source_title	Title of the source document or page
source_url	Primary source URL
source_type	One of us_federal_agency, us_state_agency, us_local_government_or_utility, intergovernmental_organization, university, survey_publisher or industry_association_or_foundation
source_license_note	public_domain_us_federal, government_fact_cite_source or referenced_figure_source_copyright. See LICENSE
verification_status	Verification state and date
review_flags	Caveats a reader should know about. Blank if none
wsg_page_url	Companion page
last_checked	Date the source was retrieved

Each statistic is a full sentence, so there are no separate numeric value/unit columns. Splitting them out by machine was not reliable enough to publish. The statistic text is the authoritative value.

Suggested citation

Water System Guide (2026). Hard Water Map & Water Quality Statistics (2026) (Version 1.0.0) [Data set]. https://watersystemguide.com/guides/hard-water-statistics/ Zenodo. https://doi.org/10.5281/zenodo.23534609

When you use a single figure, please also cite the original source listed in that row.

Updates

The data is refreshed quarterly, with the next review by 2027-01-11. It is also updated within 30 days of a new EPA UCMR, DWINSA, USGS Mineral Commodity Summaries or Gallup environment release. New versions get a new version number.