What's in Tap Water Anyway?

Ever wonder what's in tap water anyway?

The WHO drinking-water fact sheet is about global access. U.S. city tap is treated and regulated. It can still contain leftover chlorine, byproducts, metals from pipes, and other traces. A home filter is for those leftovers — not a substitute for a water system that was never treated.

What's in Tap Water?

In most of the United States, municipally treated tap water meets legal standards. That is not the same as “nothing left in the glass.” Broken pipes and old solder can add metals. Utility reports list what they test for.

Our family uses a Berkey gravity system on city tap water. Assemble it, prime the elements, pour tap in the top. Current official replacements: Phoenix filters.

Chlorine and Chloramine

Utilities add these so treated water stays stable in the pipes. Combined with organic matter they form THMs such as chloroform. EWG and others discuss long-term research on some byproducts. Carbon gravity filters are built to reduce residual chlorine and many of those byproducts.

Fluoride

Many U.S. cities add fluoride. Some studies have looked at high exposure and IQ; that research is debated. Fluoride compounds also appear in some industrial uses. PF-2 add-ons reduce fluoride on a full-size Berkey. The main elements are not a fluoride filter by themselves.

Other leftovers

EPA contaminant types: EPA CCL overview. Cities remove a lot and create new disinfection byproducts in the process. Sediment is usually a taste issue. Chemicals and metals are the reason people add a kitchen filter.

Minerals

Gravity carbon leaves calcium, magnesium, and other minerals that were already in the tap. That is why Berkey water does not taste like RO water.

What People Test For

• Radioactive elements in some regional supplies (read your report)
• Chlorine and chloramine byproducts
• Fluoride if you want it lower than the city dose
• Lead, mercury, arsenic
• Pesticides and solvents
• PFAS / PFOA
• Pharmaceutical traces
• Rust and sediment from old pipes

Water quality quiz then pull the CCR from your utility.

Radioactive leftovers

Some regions test for uranium and related elements. That is a report question, not something you diagnose by looking at the glass.

Chemicals and metals

Lead from old solder is the classic household add-on. Mercury and arsenic show up in some groundwaters — wells need their own lab panel. City tap is still the intended fill for a Berkey.

How You Tell What Is in the Tap

You usually cannot see it. Taste and color are clues, not a lab. Ask the utility for the CCR. Pay a certified lab if you want metals or PFAS numbers.

What Boiling Does

A boil-water notice is a utility order. Follow it. Boiling does not remove chlorine byproducts, metals, or PFAS. A gravity filter does not replace the notice. After the notice lifts, you are back to filtering city tap.

What We Do at Home

Read the report. Filter the kitchen tap. Quiz or contact us if you want a size.