What you are actually buying from a utility

A public water system treats to enforceable federal limits and must deliver you a Consumer Confidence Report by July 1 each year naming its source, the regulated contaminants it detected, and the health effects of anything found in violation of a health standard.

That is a real guarantee, and more than a private well owner gets. It is also bounded in three specific ways, and those three bounds are what the rest of this cluster exists to address.

What your water utility does not handle

Household plumbing, downstream of every sample

Lead and copper are usually picked up after the water leaves the utility’s control. EPA attributes copper to “corrosion of household plumbing systems”, and states that where a home has a lead service line, “these pipes are typically the most significant source of lead in the water” — more likely in older cities and homes built before 1986.

All of that sits downstream of the distribution system a utility samples, which is why a compliant system-wide result is not a measurement of your kitchen tap. Only a first-draw test of that tap is.

A system can exceed a health goal and remain fully compliant. EPA explains that a result below the Maximum Contaminant Level Goal carries “no known or expected risk to your health”, while one above the Maximum Contaminant Level means the system is in violation of EPA regulations.

Between those two figures the water is legal and nothing in the report flags it. For lead that band is everything, because EPA sets the goal at zero on the basis that no safe level of exposure exists. Compliance is a legal status rather than a health verdict.

Regulated does not yet mean monitored

A federal standard existing does not mean the data exists. EPA gives public water systems until 2027 to complete initial PFAS monitoring and to begin informing the public of the levels found, and until 2029 to reduce PFAS where monitoring shows the limits are exceeded.

The Lead and Copper Rule Improvements require the vast majority of systems to replace lead service lines within ten years, against up to 9 million homes and businesses still connected through legacy lead pipes. Until those clocks run out, a silent report can reflect an absent test rather than an absent contaminant.

Start here, in this order

First, read the report. It costs nothing, arrives annually, and every decision below depends on something in it.

→ How to read your water quality report → And what to test yourself, once you have read it

Then identify your disinfectant. The report names it, and it decides which filter claim you need — chlorine and chloramine are separate certifications.

→ Chlorine vs chloramine

Then work the gaps that apply to you.

If your concern is Read Because
Lead Lead The health goal is zero, and your utility owes you an inventory
Choosing a lead filter Lead-certified filters 615 certified models, and no whole-house system among them
Blue-green stains, metallic taste Copper Visible evidence of corrosion — and a free warning about lead
Black or brown staining Manganese Health guidance exists, and no rule obliges a utility to meet it
PFAS PFAS Certification does not yet demonstrate reduction to EPA limits
Fluoride Fluoride Two federal numbers, and the cosmetic one is half the health limit
Choosing a fluoride filter Fluoride-certified filters One format holds the claim, and carbon is not it
Nitrate on the report Nitrate-certified filters Boiling concentrates it, and 84 models are certified
Taste, odour, chlorine smell Chlorine vs chloramine The two need different certified claims
A chloraminated supply Chloramine-certified filters 137 certified models, and no pitcher holds the claim
TTHM or HAA5 on the report Disinfection byproducts An annual average at a sampling point, and a route you inhale
Choosing a TTHM filter TTHM-certified filters 149 models treat a tap; four treat the main
A TDS meter reading TDS It measures aesthetics, and detects nothing with a health limit
Chromium on the report Chromium-6 One limit covers both forms, and assumes the worse one
Sediment, grit, cloudiness Micron ratings Absolute and nominal ratings are not the same promise
Microplastics Microplastics One claim, widely held, and no federal limit to measure against
Cryptosporidium, Giardia Cysts EPA requires removal, not disinfection — so it is a pore size
Turbidity on the report Turbidity A cloudiness figure standing in for a pathogen check
Considering reverse osmosis Reverse osmosis One required claim, and it is the one with no health limit
Radionuclides on the report Radium and uranium Four regulated, one with a certified filter claim
Choosing a filter shape Filter types The form decides which claims are even available
Nitrate on the report Nitrate Acute risk, 24-hour notice, and carbon does nothing
Taste, smell or staining Taste, smell and colour Fifteen standards, none of them enforced
Which technology to buy Best Available Technology EPA names carbon once in fourteen inorganics
Contaminants with no limit Unregulated contaminants Watched and monitored, but nothing to comply with
Algal bloom advisory Cyanotoxins Ten-day advisory values, no enforceable limit
Radon on a water test Radon in water A 1999 proposal, never finalised; test the air
Legionella concern Legionella Regulated with no limit; grows after the meter
Old asbestos cement mains Asbestos The pipes are the source EPA names
Considering a distiller Distillation Broad reach, and no searchable claim to check
Lead at a school or nursery School drinking water Voluntary federally, and the claim name misleads
Medicines or hormones Pharmaceuticals No limit, no monitoring, and a large certified field
Coliform on the report Coliform bacteria An indicator that starts an assessment, not a violation
Your system draws ground water Ground water systems Disinfection is not required; the rule targets risk
Pressure loss or a main break Cross-connections and backflow The one route treatment cannot reach
Taste differs by street or season Water age One variable behind several symptoms
Street work or a main break Main breaks Routine events with a real mechanism
Choosing a cyst filter Cyst-certified filters 1,104 certified models, and four of them are pitchers
Hardness and scale Softener sizing The arithmetic, and the running cost nobody quotes
Sodium in softened water Softened water and sodium Worked against the FDA Daily Value at your own hardness
Whether to buy bottled Bottled vs tap Two aligned regulators, and the report you stop receiving

Choose where to treat, by exposure route

One rule settles it, and it is about exposure route rather than budget. EPA states point-of-use treats only the water consumed, and that whole-house is warranted for contaminants that “easily turn into gases and may pose a risk when inhaled, such as when showering” — or for scaling, staining and odour.

  • Choose point-of-use if the contaminant reaches you by drinking it: lead, nitrate, arsenic, PFAS, cysts. Treat the tap you actually drink from.
  • Choose whole-house if EPA names it as one that turns into a gas and may be inhaled while showering, or if the problem is scaling, staining or odour, which affect every fixture.
  • Choose both if you have one of each — hardness plus lead is the common pairing — and mind the order they go in.

→ Point-of-use or whole-house

The rule that governs every purchase here

Certification claims vary by product. A system certified to a standard is not certified against everything in that standard: under NSF/ANSI 58, TDS reduction is the only required claim, and lead, nitrate, arsenic and cyst reduction are all optional.

Ask which standard and which claim, then check the listing rather than the box.

→ What each NSF standard covers → The seven questions that decide the purchase → Well water treatment, if you are not on a public system → Ground water systems and the rule that governs them → Cross-connections and backflow: the route no treatment reaches → Water age: why the same supply differs street to street → Main breaks and new pipe: what a repair does to your water → Home plumbing materials: the last stretch before the glass