Water quality recommendations on this page are informational. Test results vary by location. Contact your state health department or a certified lab for guidance specific to your water supply.
WELL WATER TESTING
Well Water Testing Guide: What to Test, When, and What Results Mean
Private well owners are their own water utility. This guide covers what to test, how often, how to collect a sample, and what to do when results come back.
Last reviewed: May 2026
Testing frequency table
Not every contaminant needs to be tested every year. This table shows the standard schedule for private well owners.
| Contaminant | Test frequency | Why |
|---|---|---|
| Bacteria / coliform | Every year | High health risk. Can change quickly after rain or nearby animal activity. |
| Nitrates | Every year | Leaches from fertilizers and septic systems. Dangerous for infants under 6 months. |
| pH and hardness | Every 3 years | Changes slowly. Affects taste, plumbing, and filter performance. |
| PFAS | Every 3 years (minimum) | EPA 2027 rule sets 4 ppt limit for public systems. Use that as your benchmark. |
| Arsenic | Once at new well, then every 5 years | Comes from natural geology. Stable over time. |
| Lead | Once at new well | Plumbing concern. Test again after major plumbing work. |
Lab testing vs DIY test kits
Certified lab tests
- Results are legally certified
- Can detect PFAS, arsenic, nitrates accurately
- Required for real estate transactions or legal disputes
- Turnaround: 5 to 14 days
- Cost: $75 to $400 depending on panel
DIY test kits
- Good for quick bacteria and lead screening
- Cannot detect PFAS
- Not certified, not usable for legal purposes
- Turnaround: minutes to hours
- Cost: $20 to $50
Use a DIY kit if you want a fast check between annual lab tests. Use a certified lab for anything you will act on.
How to collect a sample
- 1.Remove any aerators or filters from the tap you are sampling. These can mask contamination that is in your water supply.
- 2.Run cold water for 2 to 3 minutes. This flushes water that has been sitting in the pipes and gives you a representative sample from the well itself.
- 3.Use the sterile container your lab sent. Do not touch the inside of the lid or bottle. Contamination from your hands will affect bacteria results.
- 4.Fill to the line marked on the container. Some labs send multiple bottles for different test types. Label each one clearly.
- 5.Refrigerate the sample immediately. Mail it within 24 to 48 hours using the pre-paid shipping label your lab provides.
Reading your results
Lab reports list each contaminant, your measured level, and the EPA maximum contaminant level (MCL). The MCL is the legal limit for public water.
Your well is not legally required to meet EPA MCLs. But they give you the best available benchmark. A result below the MCL is generally considered acceptable. A result above the MCL means you should take action.
Some reports also show EWG (Environmental Working Group) health guidelines. These are stricter than EPA limits in most cases. A result between the EPA MCL and EWG guideline is a gray area worth watching.
Keep every test result. Build a file for your property. Trends over time matter as much as any single result.
What to do with results
Results within safe limits: test again on schedule, no action needed now.
Results above a MCL for bacteria or nitrates: boil water advisory for drinking and cooking. Call your county health department. Have the well inspected.
Results above the EPA PFAS benchmark of 4 ppt: see our guide on what to do after a positive PFAS test. Do not drink the water unfiltered while you sort this out.
Frequently asked questions
Can I test my well water myself?
Yes, for basic screening. DIY strips can check for bacteria, lead, and pesticides in minutes. But strip tests are not lab-certified. For PFAS, arsenic, nitrates, and anything you will act on, use a certified lab. Lab results hold up legally; strip tests do not.
How do I collect a well water sample?
Run cold water from a kitchen tap for 2 to 3 minutes first. This flushes standing water from the pipes. Use the sterile container your lab provides. Fill it without touching the inside of the lid or bottle. Refrigerate and mail within 24 to 48 hours.
What is a maximum contaminant level (MCL)?
An MCL is the legal limit for a contaminant in public water. For example, the EPA MCL for nitrate is 10 mg/L and for PFOA is 4 parts per trillion. Your well is not legally required to meet these limits, but they give you a clear benchmark for action.
What should I do if my results show high PFAS?
First, stop drinking unfiltered water from that source. Then confirm with a second test from a different lab. Contact your county or state health department. Then choose a filter rated for PFAS removal. Reverse osmosis and activated carbon both work.