Arsenic Water Test: Why Every Well Needs One

A good arsenic water test can save you from spending $1,500 to $5,000 on the wrong treatment system. The frustrating part is that arsenic has no taste, no smell, and no color in water, so your well can look perfectly clear and still need attention. For many rural homeowners, the first real clue comes from a lab report that costs far less than a service call.

If your home has a private well, arsenic testing is not something the water company handles for you. There is no water company. You are the water manager, which means you decide when to test, what to test for, and what to do with the results.

That can sound like a lot, but it does not have to be complicated. The main job is to get a certified-lab result, compare it to the EPA drinking water limit, and then choose the next step based on the number. This guide walks through when to test, what kind of arsenic water test to buy, what the results mean, and how to avoid wasting money on guesses. Put arsenic on the same calendar as your annual panel in the well water testing guide, and retest after well work described in well pump maintenance.

Why arsenic is different from many well problems

Some well water problems announce themselves. Iron can leave orange stains. Sulfur can smell like rotten eggs. Hard water can crust up faucets and shorten water heater life. Coliform bacteria is another silent problem that only a lab catches — often on the same annual sample.

Arsenic is different. You usually cannot see it, smell it, or taste it. A glass of water with arsenic can look just like a glass of water without it.

That is why an arsenic water test matters even if your water seems fine. According to EPA drinking water standards, the federal maximum contaminant level for arsenic in public drinking water is 10 micrograms per liter, also written as 10 parts per billion or 0.010 milligrams per liter. Private wells are not regulated the same way public water systems are, but that 10 ppb number is still the common comparison point homeowners use.

Arsenic can occur naturally in rock and soil. As groundwater moves through those materials, arsenic can dissolve into the water that feeds your well. It can also vary by region and even from one property to the next. Your neighbor’s clean test does not prove your well is clean.

The CDC and state health departments recommend testing private wells because the only dependable way to know is with a lab result. If you have health concerns or a high result, confirm the result with a certified lab and contact your county health department for local guidance.

Who should get an arsenic water test

If you own a private well and you do not have a recent arsenic result, you should test. That is the plain answer.

A recent result means you have a lab report in your records, not a memory that someone tested the well years ago. For a home purchase, a test from the seller may be useful, but it is still worth checking what was actually tested. Many basic real estate water tests focus on bacteria, nitrate, and sometimes lead, but they may not include arsenic unless it was specifically requested.

You should make arsenic testing a priority if any of these apply:

• You have never tested your well for arsenic.
• You are buying or selling a home with a private well.
• You have a new well.
• Your well was repaired, deepened, or replaced.
• You installed new treatment equipment and want to confirm it works.
• You live in an area where arsenic is known to occur in groundwater.
• You rely on well water for drinking, cooking, coffee, ice, or baby formula.
• You have an old test result but no copy of the actual lab report.

Arsenic is not only a “bad well” problem. Some wells with high arsenic produce plenty of water, have no odor, and pass a bacteria test. A bacteria test tells you about bacteria. It does not tell you whether arsenic is present.

For a broader look at private well care, see our well water guide. The big idea is simple: test for the things you cannot see before you shop for treatment.

When to test your well for arsenic

For most private well owners, arsenic does not need to be tested every few months. But it should be tested at least once, and it should be retested when something changes.

A practical schedule looks like this:

• Test for arsenic when you first start using a private well.
• Retest if the well is repaired, replaced, deepened, or the pump is changed.
• Retest before buying a home with a private well, even if the water looks clear.
• Retest after installing arsenic treatment, usually after the system has flushed and settled according to the installer or manufacturer instructions.
• Retest if your county or state health department announces local arsenic concerns.
• Keep the lab report with your home records so you know the date, result, and lab method.

Some homeowners also choose to retest every 3 to 5 years for peace of mind, especially in areas where arsenic is common. That is a reasonable habit if you drink the water every day.

Annual testing is still important for other well concerns. Many health departments recommend yearly testing for bacteria and nitrate. If nitrate is part of your well test, remember the EPA maximum contaminant level is 10 mg/L as nitrate-nitrogen, and EPA warns that infants under 6 months who drink formula mixed with high-nitrate water are at special risk. For nitrate results or infant feeding questions, confirm with a certified lab and your county health department.

What kind of arsenic water test should you buy

For arsenic, use a certified laboratory test. That can be done through your county, state-certified lab, local water testing company, or a certified-lab mail-in kit.

Home screening strips can be useful for some water chores, but arsenic is not the place to rely on a quick color pad. You are dealing with very small numbers, usually parts per billion. A certified lab is the better tool because it can measure low levels and give you a written result you can keep.

When comparing an arsenic water test, look for these points:

• The test specifically lists arsenic, not just “metals” in vague language.
• The lab is certified for drinking water testing in your state or uses certified methods.
• The reporting limit is low enough to compare with 10 ppb.
• The instructions are clear about flushing, bottle filling, shipping, and timing.
• The report will show the result in ppb, micrograms per liter, or milligrams per liter.
• Customer support can explain units without selling you treatment first.

A single-contaminant arsenic lab test often costs in the tens of dollars. Broader well panels commonly cost more, often around $100 to $300 depending on what is included. A broader panel may be the better value if you have not tested your well in years, because arsenic is only one of several common private-well concerns.

If you are buying a mail-in kit, check whether shipping is included and whether return shipping has a deadline. Some tests are time-sensitive once the sample is collected. Waiting a week to mail a sample can ruin the value of the result.

Arsenic test options compared

The best choice depends on why you are testing. A home buyer, a long-time owner, and someone checking a treatment system may not need the same panel.

Test option	Best for	Typical cost range	Main caution
Arsenic-only certified lab test	You already test for other items and just need arsenic	Often tens of dollars	Does not tell you about bacteria, nitrate, lead, or other metals
Broad certified well water panel	You have no recent full well report	Commonly about $100 to $300	Make sure arsenic is actually included
County or state lab test	Local guidance and official-style reporting	Varies widely by state and county	Some programs have limited hours or sample drop-off days
Treatment company test	Early screening before a quote	Sometimes free or low cost	Confirm high results with an independent certified lab before buying equipment
Home screening kit	Curiosity or rough screening only	Usually lower cost	Not the best choice for arsenic decisions

If your goal is to decide whether to install treatment, pay for a certified lab result first. Spending $50 to $300 on good testing before spending thousands on equipment is usually the cheaper path.

How to collect the sample without spoiling the result

Your lab kit should come with instructions. Follow those instructions over any general advice online. Different labs use different bottles, preservatives, and hold times.

That said, most good sampling habits are common sense:

• Read the instructions before you turn on the faucet.
• Use the bottle the lab provided.
• Do not rinse a preserved bottle unless the instructions tell you to.
• Choose the faucet the instructions recommend, often a cold-water tap.
• Remove aerators or screens if instructed.
• Avoid sampling from a hose, swing-arm faucet, or dirty utility sink unless directed.
• Let the water run for the recommended time.
• Fill to the marked line if there is one.
• Keep the bottle clean and capped.
• Mail or deliver it within the required timeframe.

Before you sample, decide what question you are trying to answer.

If you want to know what is in the well before treatment, collect from a point before filters, softeners, reverse osmosis, or other treatment if you have safe access and the lab approves that location.

If you want to know what you are drinking at the kitchen sink, collect from the drinking water tap.

If you have an under-sink reverse osmosis system, you may need two samples: one before treatment and one after treatment. The first tells you the well’s condition. The second tells you whether the system is reducing arsenic at the tap.

Do not collect a sample right after shocking the well, replacing plumbing, or changing filters unless the lab or health department tells you to. Those events can affect results. If the test is for a home sale, ask the buyer, lender, or local authority what timing and sample location they require.

How to read your arsenic water test result

Your lab report may use one of three common units:

• ppb, which means parts per billion.
• ug/L or micrograms per liter.
• mg/L or milligrams per liter.

For arsenic in drinking water, 10 ppb equals 10 ug/L, and 10 ug/L equals 0.010 mg/L. Those are three ways of writing the same EPA limit for public water systems.

Here is a simple way to think about the result:

Lab result	What it means	Sensible next step
Not detected	Arsenic was below the lab’s detection limit	Keep the report and retest when the well changes
Detected below 10 ppb	Arsenic is present but below the EPA public-water limit	Keep records and ask your health department if local guidance is stricter
Around 10 ppb	The result is near the EPA limit	Confirm with a second certified-lab sample before making a major purchase
Above 10 ppb	The result is above the EPA public-water limit	Confirm the result, use an appropriate drinking-water plan, and contact your county health department
Much higher than 10 ppb	The well may need prompt attention for drinking and cooking water	Confirm with a certified lab and get local health department guidance before choosing treatment

Do not panic over one number, but do not ignore it either. Sampling mistakes can happen. Lab errors are uncommon but possible. Plumbing and treatment setup can also affect where arsenic shows up.

If the result is high, the right move is to confirm it with a certified lab, then talk with your county health department or state well program. They can help you understand local geology, whether neighboring wells have similar results, and what treatment approaches are commonly used in your area.

If arsenic is high, do not buy equipment blindly

A high arsenic water test does not automatically tell you which treatment system to buy. Arsenic treatment depends on the form of arsenic, the level, the flow rate, the water chemistry, and where you want treated water.

Common treatment options include point-of-use reverse osmosis, adsorptive media, anion exchange, and some whole-house systems. The right answer depends on the lab report and the home.

Point-of-use treatment means treating water at one tap, usually the kitchen sink. This is often used for drinking and cooking water. A basic under-sink reverse osmosis system may cost a few hundred dollars for the unit, with more for professional installation. Higher-end systems and difficult installs cost more.

Whole-house treatment means treating water as it enters the home. This can be useful when the household wants treated water at every tap, but it is usually more expensive. Many whole-house arsenic systems run into the thousands of dollars once equipment, installation, media, and follow-up testing are included.

Before you buy, ask the seller or installer these questions:

• Is this system designed to reduce arsenic at my measured level?
• Does it handle the type of arsenic in my water?
• What other water conditions affect it, such as iron, manganese, pH, hardness, sulfate, or silica?
• What flow rate can it treat?
• How often will filters or media need replacement?
• What does annual maintenance usually cost?
• Where will we collect the follow-up sample?
• What happens if the post-treatment test is still above 10 ppb?

Any company can say a system “helps with arsenic.” You need a system matched to your water and verified by a follow-up lab test.

Whole-house or kitchen-sink treatment

For arsenic, many families focus first on water used for drinking, cooking, coffee, tea, ice, and mixing formula. That is why under-sink treatment is common. It can be a practical first step when the main concern is ingestion.

Whole-house treatment may make sense if arsenic is high, if multiple taps are used for drinking, if the household wants simpler daily habits, or if local health officials recommend it. It may also be preferred when a home is being prepared for sale and the buyer wants a permanent installed solution.

The tradeoff is cost and maintenance. A kitchen-sink system might have filters changed every 6 to 12 months, depending on use and water quality. A whole-house system may need media changes, prefilters, backwashing, drain access, and periodic service. Those costs should be part of your decision before you sign.

If you install treatment, schedule a follow-up arsenic water test after the system is running normally. Then keep testing on the schedule recommended by the manufacturer, installer, or health department. Treatment can work well, but it is not a one-and-done purchase. Filters exhaust. Media wears out. Settings get changed. A lab test is how you know the water at the tap is still where it should be.

What not to do after a high arsenic result

A high result can make any homeowner feel rushed. Slow down enough to avoid these common mistakes.

Do not assume boiling helps. Boiling water does not remove arsenic. Because boiling reduces water volume, it can concentrate some contaminants rather than fix them.

Do not rely on a pitcher filter unless it is specifically certified for arsenic reduction and matched to your situation. Many common carbon filters are sold for taste, odor, and chlorine, not arsenic.

Do not buy a softener and expect it to solve arsenic. Water softeners are mainly for hardness. They are not a general-purpose safety system.

Do not treat the whole house before confirming where the problem is and what the treatment must remove. A second lab test is cheap compared with the wrong equipment.

Do not forget maintenance. The best system on paper can fail if filters are not changed or media is not replaced.

Do not throw away the lab report. Keep the original PDF or paper copy with your well records, treatment invoices, and filter change dates.

A practical buying checklist

Use this checklist before you order an arsenic water test or treatment quote.

• I know whether I need an arsenic-only test or a broader well panel.
• The test uses a certified lab, not just a visual strip.
• Arsenic is clearly listed on the test panel.
• The reporting units will let me compare the result to 10 ppb.
• I understand where to collect the sample: before treatment, after treatment, or at the drinking tap.
• I can ship or deliver the sample within the lab’s required timeframe.
• I will save the lab report with my home records.
• If arsenic is near or above 10 ppb, I will confirm with a certified lab.
• I will contact the county health department for health-related guidance.
• I will not buy treatment until I know the actual arsenic result.
• If I buy treatment, I will budget for follow-up testing and filter or media replacement.
• I will set a reminder so the next test does not depend on memory.

That last item matters more than most people think. Plenty of well owners do the right thing once, then lose track for five or ten years. A reminder is cheaper than guessing.

What a good well record should include

A private well does not come with a monthly water bill that tracks everything for you. Your records are the paper trail.

Keep a folder, binder, or digital file with:

• Well completion report, if you have it.
• Pump and pressure tank service records.
• Water test reports, including arsenic.
• Treatment equipment manuals.
• Filter and media replacement dates.
• Installer names and phone numbers.
• Notes about plumbing changes.
• Dates when the well was shocked, repaired, flooded, or opened.

If you ever sell the home, these records can help answer buyer questions. If you ever need treatment, they help the installer understand what has already been done. If a lab result changes, they help you and your health department look for possible reasons.

For homes that also have a septic system, keep those records too, but do not mix them together. Septic maintenance and well water safety are connected around the property, yet the records serve different jobs. Our septic guide covers the tank side of that rural-home routine.

How much should you budget

Here is a simple planning budget for a homeowner who has no recent arsenic report.

If you only need arsenic, plan on a certified lab test in the tens of dollars. If you want a fuller look at your well, plan on roughly $100 to $300 for a broader certified panel, depending on what is included. Prices vary by state, lab, shipping, and local programs.

If the result is below 10 ppb and nothing else looks concerning, your next cost may simply be future testing.

If the result is near or above 10 ppb, budget for a confirmation test before treatment. That may feel repetitive, but it is a sensible step before spending serious money.

If treatment is needed, a kitchen-sink system is often the lower-cost starting point, while whole-house treatment commonly costs much more. The purchase price is not the whole cost. Ask about replacement filters, media, service visits, electricity if any, drain requirements, and follow-up lab testing.

A realistic first-year plan might look like this: pay for a lab test, confirm if needed, get two treatment quotes if arsenic is high, install the chosen system, then pay for a post-treatment lab test. That process may take a few weeks from first sample to final result, longer if contractors are busy or special equipment is needed.

The bottom line

An arsenic water test is one of the most useful tests a private well owner can buy because it checks for something your senses cannot catch. Clear water is not proof. A bacteria test is not proof. A neighbor’s result is not proof.

Start with a certified lab. Compare the number to the EPA 10 ppb drinking water limit. Confirm high or borderline results. Talk with your county health department for health-related guidance. Then choose treatment only if the lab result shows you need it.

If you want help keeping track, Tank & Well can email you before your next well water test is due. Set up free reminders for pump-outs and water testing in a couple of minutes, with no app, no account, and no charge.