Concerned about arsenic in well water? Start with an arsenic test from a state-certified laboratory, not a filter choice. A water sample is the only way to know how much arsenic is present. Use that result to discuss your next step with your local health department.
The Washington State Department of Health’s private-well guidance states:
We recommend that water used for drinking or food preparation contain no more than 10 parts per billion (ppb) arsenic.
That is private-well advice, not a promise of zero risk at 10 ppb. If your result is above 50 ppb, Washington DOH recommends that you stop using the water immediately for drinking and food preparation. Above 500 ppb, contact your local health department or Washington DOH before choosing an option.
Generated illustration, not an arsenic test result. The generic strip shown is not the recommended laboratory test for arsenic.
Table of Contents
Where Does Arsenic in Well Water Come From?
Arsenic is a naturally occurring chemical element. As water moves through rock and soil that contain arsenic, some of it can dissolve into the water. Washington DOH describes this natural process in its private-well guidance.
That explanation cannot tell you the concentration in your own well. A local concern is a reason to arrange testing, not a substitute for your result.
How to Arrange an Arsenic Well Water Test
The CDC’s current well-water testing guidance recommends a state-certified laboratory. It also advises asking your health or environmental department which additional chemicals, including arsenic, to test for where you live.
When you contact the lab:
- Ask specifically for an arsenic test. Confirm that arsenic is included rather than assuming a general well-water panel covers it.
- Get the lab’s sample instructions and container requirements. Follow those instructions rather than a generic sampling method.
- Explain whether you want to test the untreated well water or check water from an existing treatment system. Ask the lab where to collect the sample.
- Ask the lab to explain the reported concentration and units. Keep the report with the sample date and location.
For the broader annual checklist, use our guide to getting well water tested. This article focuses on the arsenic result rather than repeating that routine.
What Does Your Arsenic Result Mean?
Read the number and its units together. The Washington guidance uses parts per billion, abbreviated ppb. If your report uses different units or wording you do not understand, ask the lab to explain it before comparing numbers.
Public-System Standard Versus Private-Well Advice
Washington DOH explains that the federal drinking-water requirement for public suppliers is 10 ppb or less arsenic. The CDC states that EPA rules for public drinking water systems do not apply to privately owned wells.
That does not mean local rules never apply. Washington DOH notes that some Washington counties have private-system arsenic rules, although there is no statewide private-well standard. Ask your health department what applies where you live.
The 10 ppb recommendation is also not a zero-risk line. Washington DOH says that reducing arsenic below 10 ppb can lower the chance of health effects, but does not completely eliminate that risk.
Use the Washington Guidance to Plan Your Next Step
These are Washington DOH recommendations. Your local health department can help apply them to your result and local requirements.
- At or below 10 ppb: The result falls within the quoted recommendation for drinking and food preparation. It does not establish zero arsenic risk or show that other contaminants are absent.
- Between 10 and 50 ppb: Washington DOH recommends against drinking the water or using it for food preparation over the long term. Contact your health department to discuss an alternative supply and a plan to reduce exposure.
- Above 50 ppb: Stop using the water immediately for drinking and food preparation, as Washington DOH recommends. Use a safe alternative source while you arrange next steps.
- Above 500 ppb: Also contact your local health department or Washington DOH before choosing a treatment or other option. Ask for guidance on other household water uses as well.
Do not read these drinking-water recommendations as a general clearance for bathing or other uses. If you need advice about those uses, take your result to your health department.
Choosing Treatment for Arsenic in Well Water
While you consider options, Washington DOH says that drinking and cooking with bottled water can reduce exposure immediately. It also advises asking the supplier about impurities, including arsenic. The CDC recommends considering bottled water or another safe source when testing finds harmful chemicals.
Check the Exact System, Not Just Its Type
Many filters improve taste or odor without removing arsenic. Washington DOH states that some systems using reverse osmosis, distillation, or special filtration material can reduce arsenic. This does not establish that every system in those categories will work for your water.
Take your lab report into the treatment discussion. Washington DOH notes that water quality affects both treatment performance and maintenance needs. It recommends NSF-certified equipment and testing after installation and routine maintenance.
Before choosing a system, ask:
- Is this exact model certified for arsenic reduction, rather than only a different contaminant?
- Is it suitable for the water described in my lab report?
- Which taps will it treat?
- What maintenance does it require, and how will we verify the treated water afterward?
A point-of-use system treats water at a single tap. A point-of-entry, or whole-house, system treats water used throughout the house. Neither label alone establishes arsenic reduction. Our water filtration guide explains the broader treatment choices; use your arsenic result and the exact certification when making this decision.
Generated equipment illustration. The tank is not presented as an arsenic-removal device or an installation guide.
Verify the Water After Treatment
Have the treated water tested after installation and after routine maintenance, as Washington DOH recommends. Do not use an improved taste or a completed installation as proof that arsenic has been reduced.
Ask your lab and health department how to check ongoing performance. Keep the results with the system’s maintenance records so you can compare the water before and after treatment.
Frequently Asked Questions
Does a General Well Test Include Arsenic?
Do not assume it does. The CDC lists arsenic among the additional chemicals to discuss with your health department. Ask the lab to confirm what your test includes. For a separate contaminant question, our nitrate in well water guide covers nitrate-specific testing and interpretation.
How Often Should I Test for Arsenic?
Ask your local health department for a schedule suited to your well. Washington DOH says arsenic levels can vary during the year. Its guidance recommends testing once in late summer and again in early spring to check for seasonal differences. This is Washington’s advice, not a universal testing schedule for every location.
Would a New Well Solve the Problem?
Not necessarily. Washington DOH says a well at a different location or depth may or may not provide water with acceptable arsenic levels. Discuss that option with your health department rather than treating a new well as a guaranteed solution.
Your Next Step
If you do not have an arsenic result, contact a state-certified lab and request one. If you already have a result, discuss the concentration and units with your health department. For arsenic in well water, the useful sequence is specific: test, interpret the result, choose a suitable response, and verify any treatment with another water test.
