Well Water Testing: The Complete Guide for Private Wells (2025)

Well water testing means checking your private well water for contaminants that can affect safety, taste, odor, staining, or plumbing.

A "test" can mean different things:

• A basic annual check for common indicators like bacteria, nitrates, and general water chemistry
• A broader screening panel that looks for metals, minerals, and other potential contaminants
• A targeted test for a specific concern, like lead from plumbing, arsenic from geology, or PFAS in known contamination areas

Testing is not the same as treatment. A test tells you what's in your water and at what level. Treatment is what you do afterward if results show a problem.

With a private well, you decide when to test and what to test for.

Public water systems are tested and managed under formal requirements. Private wells are different. Most places don't monitor them for you, which is why testing is so important for well owners. (EPA)

If you're renting a home with a private well, responsibility depends on your lease and local rules. If testing matters to you, ask the property owner what testing has been done and when.

This is the question most well owners start with: what tests do I need?

Think of testing in three categories:

1) Baseline Annual Tests

Test your well water at least once each year for:

• Total coliform bacteria
• Nitrates
• Total dissolved solids (TDS)
• pH

This set catches common issues and helps you spot changes over time. (CDC)

Many homeowners also include E. coli as part of bacteria testing, since labs usually report it alongside total coliform.

2) Periodic Expanded Screening

Every few years, or based on local concerns, you might test for:

• Metals like arsenic, lead, and manganese
• General chemistry like hardness, iron, and alkalinity
• Radionuclides in certain areas
• Volatile organic compounds (VOCs) if there's a nearby risk source

You don't need to test for everything every year. Test based on what makes sense for your situation.

3) Situation-Based Tests

Test when something changes. Consider extra testing when:

• Your area had flooding or your wellhead was submerged
• You had well work done (pump replacement, casing work, opening the system)
• You notice a change in taste, smell, color, or staining
• A household member is pregnant or an infant is in the home
• A neighbor reports contamination or there is a local advisory
• You are in a home purchase or sale process

If you want an organized view of common contaminants and what they mean, use: Well water contaminants guide hub

A simple approach that fits most households is:

Test at Least Annually for the Basics

Test annually for the baseline indicators: bacteria, nitrates, pH, and TDS. (CDC)

Pick a consistent time each year. Spring works well, but any regular schedule is fine.

Test Sooner When Something Changes

Don't wait for your annual test if something changes. Test right away after:

• Flooding or heavy runoff around the well area
• Well repairs or any work that opens the well system
• A well cap that was damaged or came loose
• A septic system backup, failure, or major maintenance near the well
• New construction or land disturbance near your well
• Any sudden change in water quality (odor, color, taste)

Consider Periodic Expanded Testing

Some contaminants depend on location and don't change quickly. Instead of testing for everything every year, do a broader screen every few years, then add targeted tests when needed.

Homeowners generally have four options. Each can be a good fit depending on your goal.

1) State Certified Laboratories

A certified lab is usually the best option when you need reliable results and documentation.

This works well for:

• Real estate transactions
• Yearly baseline testing
• Clear reports with units and reference points

Most certified labs offer:

• Sample bottle pickup or shipping
• Drop-off options
• Mail-in testing for certain tests
• Additional panels if you want a broader screen

2) Field Sampling Services

Some providers come to your home, collect samples correctly, and deliver them to a lab.

This helps if:

• You're testing for bacteria and want to avoid contamination
• You need documented chain of custody
• You have a complicated sampling plan with multiple taps or first-draw lead sampling
• You want a professional to handle timing and transport

3) Local Health Departments or County Programs

In some areas, local agencies provide guidance, recommended test lists, or occasional programs.

Availability varies. Some departments mainly provide education and lab lists. Others offer limited testing support.

4) Mail-In Kits and At-Home Screening

Mail-in kits can be convenient, but check carefully:

• For bacteria testing, sample handling and timing matter
• Make sure analysis is done by a qualified lab and you'll get clear results with units

At-home screening strips can be useful for quick checks, but they're not a substitute for lab testing. If a home screen suggests a problem, get confirmation from a lab.

If you've never tested before, this step-by-step guide keeps it simple and helps you avoid common mistakes.

Step 1: Decide Your Goal

Why are you testing?

• Routine annual check
• Real estate documentation
• New baby or pregnancy
• After flooding or repairs
• A specific concern like nitrate, lead, or PFAS

Your goal determines which tests to run and how careful you need to be with sampling.

Step 2: Choose a Provider and Request Containers

Most labs require specific bottles, preservatives, and instructions for each test.

Don't collect your sample in a random container. Use the bottles the lab provides and follow their instructions exactly.

Step 3: Pick the Right Sampling Location

Where you sample matters:

• A kitchen cold water tap is common for drinking water testing
• Lead testing uses specific "first draw" sampling rules
• Bacteria sampling requires removing aerators and avoiding contamination

If you have treatment equipment like a softener or filter, you might want to test:

• Before treatment, to see what's in the well water itself
• After treatment, to confirm the system is working

Step 4: Collect the Sample Correctly

Follow these practices:

• Wash your hands before sampling
• Don't touch the inside of the cap or bottle opening
• Follow instructions about flushing the tap or not flushing
• Keep the sample cold if instructed, especially for bacteria tests
• Deliver or ship within the required time window

If you're unsure, use a field sampling service. It reduces the risk of an invalid sample.

Step 5: Review Results and Keep Records

Save every lab report and note:

• Date and time sampled
• Recent weather events
• Recent well or plumbing work
• Changes in taste, odor, or appearance

Over time, your reports become a history that makes troubleshooting much easier.

Testing cost varies because you're choosing a set of tests and a service model, not buying one standard product.

Costs depend on:

• How many contaminants are in your panel
• Whether you collect the sample or hire a professional
• How fast you need results
• Shipping and logistics, especially for time-sensitive samples
• Documentation needs, like chain of custody for real estate transactions

To keep costs under control:

• Start with a baseline annual panel
• Add targeted tests based on local risk and household needs
• Do a broader screen every few years instead of every year

This is where many homeowners get confused.

Recommended Testing

Testing is recommended as routine maintenance for well ownership.

The baseline annual testing is a good starting point for most households. (CDC)

Required Testing

Whether testing is required depends on your situation:

• Real estate transactions: Some lenders, loan programs, or local practices require testing or documentation
• Local rules: Some states, counties, or towns have requirements for new wells, transfers, or specific situations

Since rules vary, check your state page for local requirements. Find well water testing requirements by state

If you're buying a home, ask early what documentation is required so you can plan for sampling and turnaround time.

Lab reports can look intimidating, but most are readable once you know what to look for.

Start with Pass/Fail Results

For bacteria tests, results are usually reported as:

• Present or Absent
• Detected or Not detected

If bacteria indicators are present, the next step is confirmation, investigation, and fixing the problem, not guessing.

Look for Units and Reference Points

Common units you'll see include:

• mg/L (milligrams per liter)
• µg/L (micrograms per liter)
• pCi/L (picocuries per liter for radioactivity)
• ppt or ng/L (parts per trillion or nanograms per liter for some contaminants)

Good lab reports show a reference value or explain how to interpret the number.

Use Public System Standards as Context

The EPA sets standards for public drinking water systems. Private wells are different, but those reference values can still be useful when discussing results with a lab, health department, or water professional.

If your report doesn't include context, ask your provider to explain:

• What the result means in plain language
• Whether you should retest
• Whether the result suggests a well issue or a plumbing issue
• What the next test should be, if any

If any result comes back high, stay calm and follow these steps.

1) Confirm the Result If Needed

Some issues are more time-sensitive than others. If you have an unexpected result, especially for bacteria, retesting is usually part of the process.

A provider or health department can help you decide whether to retest immediately.

2) Reduce Exposure When Appropriate

Take extra precautions if you have a result that suggests an immediate risk.

For example:

• If bacteria indicators are detected, many households use an alternative drinking water source until the issue is resolved and retesting confirms safety
• If nitrate is high and you have an infant or pregnancy in the home, be extra cautious while you confirm and address the issue

If you're unsure, ask your local health department or a qualified professional for guidance.

3) Identify the Likely Source

High results usually point to one of these issues:

• A wellhead vulnerability like a loose cap, broken seal, or poor drainage
• Surface water getting into the well after weather events
• Septic system problems nearby
• Naturally occurring contaminants from geology
• Plumbing and fixtures, especially for lead

4) Fix the Source Before Relying on Treatment

Treatment can help, but it shouldn't replace basic well protection.

Common well maintenance includes:

• Making sure the well cap is secure and properly sealed
• Keeping runoff and standing water away from the wellhead
• Keeping the area around the well clean and protected
• Repairing damaged casing or seals through a well professional

5) Choose a Long-Term Plan

Long-term options depend on the contaminant:

• Some issues are fixed with well repair and disinfection
• Some are best managed with point-of-use or whole-home treatment
• Some are resolved by switching to a different water source if needed

Whatever path you take, retest to confirm it worked.

You don't need a complicated checklist. A few simple habits go a long way.

• Inspect your wellhead regularly. Look for cracks, loose caps, animal activity, or pooling water.
• Keep the area around your well clean. Don't store chemicals, fuel, or fertilizers near the well.
• Manage drainage. Water should flow away from the well, not toward it.
• Maintain your septic system. Septic issues can increase contamination risk.
• Test after changes. Flooding, repairs, and sudden water quality changes are all good reasons to test right away.
• Keep records. Your testing history is one of your most useful tools.