WaterQualityDex — US drinking water systems directory
433,692 EPA-registered public water systems serving 352 million Americans, published as a searchable directory with profiles, state pages and a compare tool.
Making 433,000 water systems searchable
Nearly every American gets tap water from an EPA-registered public system — and almost nobody can name theirs, say where the water comes from, or how many people it serves. WaterQualityDex, an own product of mine, closes that gap: it takes the official SDWIS registry and republishes it as a directory where finding your utility takes seconds.
It serves curious residents, movers researching a new town's water, local journalists on a utilities beat, and industry professionals who would rather not wrestle with federal data portals.
What you can do on the site
- Search your utility. Find any water system by name or by PWSID, the EPA's official system identifier.
- Read full system profiles. System type, water source, owner, population served and EPA registration data on every page.
- Browse state by state. All 50 states, DC and the territories, from big-city utilities down to small rural systems.
- Compare two systems. A side-by-side view that shows exactly how two water systems differ.
- Check state rankings. States ranked by average violation score across their active public water systems.
- Learn about contaminants. A dedicated section explaining what can turn up in drinking water.
Coverage in numbers
The dataset spans active community and non-community systems nationwide, with the latest refresh date displayed right on the homepage. Take a look: Visit waterqualitydex.com.
How it runs
Serving 433,692 profiles quickly is a database problem before it is a web problem: a custom Laravel + PHP backend over MySQL with indexes tuned for name and PWSID lookups, and Blade templates that render every profile, state listing and comparison straight from the data. No CMS, no purchased theme, no plugins.
It is also one of the largest programmatic SEO builds in my portfolio: hundreds of thousands of indexable URLs organised into state silos, with XML sitemaps and structured data so crawlers grasp the hierarchy.
Questions people ask
Where does WaterQualityDex get its data?
From the EPA's Safe Drinking Water Information System (SDWIS), the official federal registry of public water systems in the United States. The homepage shows when the dataset was last refreshed.
What is a PWSID and do I need one to search?
A PWSID is the official identifier the EPA assigns to every public water system. You can search with it, but you don't need it — searching by your utility's name or browsing your state works just as well.
How big is the directory?
It covers 433,692 EPA-registered public water systems across all 50 states, DC and US territories — 56 jurisdictions in total — collectively serving 352 million people.
Does the site cover violations and contaminants?
Yes. State pages surface violation data, there is a ranking of states by average violation score across active systems, and a dedicated contaminants section explains what shows up in drinking water.
Adjacent data products
More own products on environmental health and safety records.