What is the most important thing to test for in drinking water?

There is no single universal answer — the most relevant tests depend on your water source and location. For public utility users, checking official compliance data for your utility is the starting point. For private well users, coliform bacteria and nitrate are commonly recommended as baseline tests. PFAS testing is increasingly relevant near industrial or military sites.

Do I need to test my water if I'm on a public water system?

Your public utility is required to test the water it delivers and report results annually in a Consumer Confidence Report (CCR). However, if you have specific concerns about lead from your home's plumbing, PFAS at the tap, or water quality changes, point-of-use testing can give you the most direct data about what is at your faucet.

What does a basic water quality test panel include?

A basic panel typically covers pH, hardness, chlorine/chloramines, turbidity, nitrate, coliform bacteria, and sometimes a handful of heavy metals. PFAS, lead, and volatile organic compounds (VOCs) usually require separate or upgraded panels. Always confirm what is included with the specific lab before ordering.

Is bottled water safer than tap water?

Bottled water is regulated by FDA, while public tap water is regulated by EPA. Neither is universally safer than the other. Some bottled water is sourced from municipal water systems. The most accurate comparison requires reviewing the specific source and testing data for both. This page covers what to test for in tap water specifically.

How do I know which contaminants are most relevant to my location?

Your state's drinking water program, local health department, and EPA's ECHO compliance database are the primary sources for location-specific water quality data. Our PFAS Watchlist and utility compliance pages surface EPA monitoring data by utility and state. Proximity to industrial sites, military bases, agriculture, and legacy contamination sites affects which tests are most relevant.

Can I test for everything in one panel?

No single panel covers all possible contaminants. Standard panels cover common indicators and regulated contaminants. PFAS requires a specialized panel (EPA Method 537.1 or 533). Volatile organic compounds (VOCs) are a separate analysis. Lead testing for household plumbing is separate from a utility-level metals panel. Tell the lab your specific concerns so they can recommend the right test combination.

Water Testing Labs

Testing Guide

What To Test For in Drinking Water

The right tests depend on your water source, location, and specific concerns. Public utility users have different starting points than private well users. This guide maps common contaminants to the situations where they are most relevant.

Last updated: 2026-05-13 · Source: EPA, CDC, state health programs

Direct Answer

For public utility users: start by checking your utility's official compliance data. Your utility tests the water it delivers. If you have specific concerns — lead from household plumbing, PFAS at the tap — point-of-use testing gives the most direct data. For private well users: coliform bacteria and nitrate are the most common baseline tests, with additional tests depending on location and local contamination concerns.

Common Drinking Water Contaminants by Situation

Not every contaminant is equally relevant to every household. The table below maps each contaminant to the situations where testing is most commonly warranted.

Contaminant	Common Source	Most Relevant For	Regulated?
Coliform bacteria / E. coli	Sewage, animal waste, surface water intrusion	Private well users (required baseline)	Yes — EPA MCL of 0
Nitrate	Agricultural fertilizer, septic systems, animal waste	Well users in agricultural areas; infant households	Yes — 10 mg/L MCL
Lead	Older household plumbing, service lines, fixtures	Homes built before 1986; anyone with older plumbing	Yes — 15 ppb action level (utilities)
PFAS (PFOA, PFOS, PFNA, and others)	Industrial sites, military AFFF firefighting foam, consumer products	Near military bases, industrial sites, utilities with PFAS records	Yes — EPA MCLs finalized April 2024
Arsenic	Natural geology, mining, smelting	Private wells in affected regions (Southwest, New England, Midwest)	Yes — 10 ppb MCL
pH	Source water chemistry, treatment	Well users and anyone with corrosion concerns	Secondary standard only (6.5–8.5)
Hardness (calcium/magnesium)	Natural geology (limestone, dolomite)	Households with scale buildup or appliance concerns	No federal MCL
Volatile organic compounds (VOCs)	Solvents, fuel, dry-cleaning chemicals	Near gas stations, industrial sites, dry cleaners	Yes — EPA MCLs for individual VOCs
Radon	Radioactive decay in rock and soil (groundwater)	Private well users in radon-affected geological regions	No federal MCL for water (proposed); state standards vary
Iron and manganese	Natural geology, corrosion	Anyone with discoloration, staining, or taste issues	Secondary standards only

This list covers common testing scenarios — not all possible contaminants. State drinking water programs publish priority contaminant lists for your region.

What To Test For — By Situation

I'm on a public water utility

Check your utility's official compliance records on this site or via EPA ECHO
Review your annual Consumer Confidence Report (CCR)
For lead concerns: test at the tap using a first-draw lead sample
For PFAS concerns: check PFAS Watchlist, then consider point-of-use testing

Look up your utility →PFAS Watchlist →

I have a private well

Minimum baseline: coliform bacteria, nitrate, pH
Additional priority tests based on your state health dept recommendations
PFAS if near industrial, military, or landfill sites
Lead if your well pump, casing, or plumbing contains older materials
Arsenic if in a geological region with documented natural arsenic

Well water testing guide →Find a certified lab →

I have a specific concern

PFAS: requires EPA Method 537.1 or 533 at a certified lab — see PFAS testing guide
Lead: use a first-draw sample protocol — do not pre-flush before collection
Nitrate: relevant for infants; any certified lab running standard water panels
Bacteria: collect sample as instructed by the lab to avoid contamination

PFAS testing guide →Lead testing guide →

Public Utility vs. Private Well: Key Differences

Public Water Utility

Regulated under EPA Safe Drinking Water Act
Required to test and report on schedule
Results published in annual Consumer Confidence Report
You can look up compliance data by utility or state
You are still responsible for lead in your own plumbing

Private Well

Not covered by federal Safe Drinking Water Act utility rules
Household is responsible for testing decisions
No required testing schedule — state guidance varies
Most state programs recommend annual coliform and nitrate tests
No CCR; results depend on what you order

Explore Testing by Concern

PFAS water testing

Lab methods, cost, and treatment for PFAS

Lead water testing

First-draw protocol and what results mean

Nitrate water testing

Especially relevant for well users and infant households

Well water testing guide

Private well baseline testing and what to order

How to read water test results

Interpreting lab reports against EPA benchmarks

Find a certified lab

State-certified and NELAP-accredited labs

Drinking Water Testing FAQs

Data Sources and Methodology

Contaminant information is drawn from EPA maximum contaminant levels, health advisories, CDC drinking water guidance, and state drinking water program resources. Regulatory status reflects federal standards; state standards may be stricter. Full methodology →

EPA Drinking Water Contaminants CDC Drinking Water Health EPA Certified Lab Directory

Last updated: 2026-05-13