Complete Well Water Testing Guide
Complete well water testing guide: what to test for, when, and how often. Annual minimums, comprehensive lab panel guide, and how to read your results.
Step-by-Step Instructions
- 1
Annual minimum tests
Coliform bacteria (E. coli and total coliform), nitrates, pH, and TDS every year. Cost: $50–150 at your county health department or state lab. Many states offer free or subsidized well testing. This catches the most common and most dangerous contamination: bacterial and nitrate contamination from surface runoff and aging septic systems.
- 2
Situational tests
After flooding: test for bacteria and nitrates within 2 weeks. After a new septic system nearby: test for bacteria every 6 months for 2 years. After any unusual taste or odor change: test for iron, manganese, hydrogen sulfide, and bacteria. After new plumbing in your home: test for lead and copper. After a nearby agricultural application: test for pesticides and nitrates.
- 3
Comprehensive baseline test
Tap Score's Well Water Test ($239) covers 130+ contaminants including arsenic, uranium, radon, PFAS, iron, manganese, hardness, bacteria, nitrates, and heavy metals. Do this once when establishing your treatment plan, whenever you move into a home with a well, or whenever situational tests show elevated results. This is the map that tells you what your well water treatment stack needs to address.
- 4
Review and act on results
Well water has no EPA MCL enforcement — you're responsible for your own action thresholds. Cross-reference your results against EPA MCLs (legal limits), WHO guidelines (health-based), and EWG health guidelines (precautionary). If bacteria: disinfect the well and retest before drinking. If nitrates above 10 mg/L: use RO or distillation for drinking water immediately, especially if infants or pregnant women are in the household.
Well Water Is Unregulated — Testing Is Your Only Protection
Private wells serve approximately 43 million Americans. Unlike municipal water, private wells have no regulatory oversight — the EPA Safe Drinking Water Act specifically exempts private wells serving fewer than 25 people. No one tests your well, issues advisories, or enforces contamination limits. The homeowner is entirely responsible for monitoring and treatment.
This matters because well water contamination is common and often invisible. Bacteria contamination has no taste, odor, or color. Nitrates above the 10 mg/L limit can cause methemoglobinemia (blue baby syndrome) in infants without any detectable change in water appearance. Arsenic, which occurs naturally in many aquifer formations, has no discernible taste at dangerous concentrations. Testing is the only way to know what your well contains.
Well Water Testing: What to Test, When, and Why
| Contaminant | Frequency | Risk Level | When Urgent |
|---|---|---|---|
| Coliform bacteria | Annually | High | After any flooding or septic failure nearby |
| E. coli | Annually | Critical | Immediately — E. coli is a health emergency |
| Nitrates | Annually | High (infants) | After agricultural activity, spring runoff |
| Arsenic | Every 3-5 years | High (varies by geology) | New well baseline; higher in granite/shale areas |
| Iron and manganese | Every 3-5 years | Low (aesthetic) | If staining, metallic taste, or orange water |
| Lead | Every 3-5 years | High if old pump/pipes | After replacing pump or any plumbing work |
| PFAS | Once (baseline) | Moderate to high | Near military bases, industrial sites, airports |
| Hardness | Every 5 years | Low (aesthetic) | If scale buildup accelerates on appliances |
| pH | Every 3-5 years | Low (corrosivity) | Low pH corrodes copper pipes and leaches lead |
How to Collect a Well Water Sample Correctly
Do not run water or disturb the system for 6 hours before sampling
Allows stagnant water (which may contain elevated lead from plumbing) to build up in the lines — shows worst-case conditions
Remove the aerator (faucet screen) before collecting the sample
Aerators can harbor bacteria and accumulated debris that artificially elevate bacterial counts — not representative of the well
Collect from the cold water tap closest to the pressure tank
Shortest path from well to sample point, minimizing cross-contamination from household plumbing
Use the pre-labeled lab bottles included with your test kit
Bacteria sample bottles contain sodium thiosulfate to stop disinfection reactions; other bottles may have preservatives specific to their contaminant panel
Keep samples refrigerated and ship within 24-48 hours
Bacteria in samples continue growing or dying at room temperature, affecting count accuracy
If Your Well Tests Positive for E. coli: Boil All Water Immediately
Recommended Test Kits
Tap Score Essential City Water Test
aquasana
$179
- ✓EPA-certified lab
- ✓Tests 111 contaminants
Tap Score Well Water Test
aquasana
$239
- ✓EPA-certified lab
- ✓Tests 130 contaminants specific to well water