PNW Well Water, A Complete Treatment Guide
Complete reference for private well owners across Eastern Washington and North Idaho. Iron, manganese, sulfur, arsenic, coliform, PFOA, what to test for, what to install.
Roughly 1 in 7 households across the Pacific Northwest drink from a private well. The EPA's Safe Drinking Water Act does not regulate private wells, the homeowner is the entire treatment plant. The seven contaminants every PNW well owner should test for: hardness, iron, manganese, hydrogen sulfide, arsenic, coliform bacteria, and (in older or industrial-adjacent areas) PFOA/PFAS. Annual testing is the WA Department of Health minimum recommendation; twice-yearly for arsenic and bacteria.
Why PNW Wells Need Treatment
The geology underneath us, basalt flows in Eastern Washington, glacial-outwash gravel through the Spokane Valley–Rathdrum Prairie Aquifer, and granite-derived soils in North Idaho, drives water chemistry that municipal systems would treat before delivery. Private well owners have to do the same work themselves.
Common conditions we see and treat across the region:
- Hardness, 7–15 gpg is typical across Eastern WA / N. Idaho wells.
- Iron and manganese, present in 50%+ of the wells we test, ranging from "barely detectable" to "8+ mg/L iron, dramatic orange staining."
- Hydrogen sulfide, the rotten-egg smell in hot water. Often paired with iron.
- Arsenic, naturally occurring in basalt formations. WA DOH recommends twice-yearly testing for private wells.
- Coliform bacteria, introduced via septic systems, surface-water intrusion after atmospheric river floods, and aging or damaged well caps.
- Low pH, common in volcanic-soil and forested-watershed wells. Causes copper-pipe pinhole leaks.
- Tannins, dissolved organics from heavy forest cover. Tea-colored water.
- PFOA/PFAS, the EPA's April 2024 final MCL is 4.0 parts per trillion. Industrial-adjacent and military-base-adjacent wells especially should test.
The Recommended Test Panel
For a brand-new well or a well changing ownership, we recommend a comprehensive test panel:
- Hardness (gpg)
- pH
- Total dissolved solids (TDS)
- Iron and manganese (mg/L each)
- Hydrogen sulfide (qualitative; lab cannot easily quantify)
- Arsenic (lab-certified)
- Total coliform and E. coli (lab-certified)
- Nitrate and nitrite (especially near agriculture)
- Lead (especially older homes / pre-1986 plumbing)
- PFOA/PFAS (where industrial-adjacent)
System Recommendations by Condition
| Condition | Recommended system |
|---|---|
| Hardness only (no iron) | Salt-based softener (Water Right Impression Plus) |
| Iron, manganese, sulfur | Water Right Iron Curtain (air-injection oxidation) |
| Iron + hardness | Iron Curtain + downstream softener |
| Bacteria (positive coliform) | Water Right Sanitizer Plus (peroxide + UV) |
| Tannins (tea-colored water) | Specialty resin softener (Impression Plus) |
| Low pH (under 6.8) | Calcite remineralizer |
| Arsenic above 10 ppb | Whole-house arsenic filter or RO at the tap |
| PFOA/PFAS | Under-sink RO with PFAS-certified stage |
| Drinking & cooking water purity (broadly) | Puronics Hydronex 7-stage RO |
Our complete Water Right authorized dealer page covers each system in more depth. Most well-water installs combine 2–4 of these technologies in a treatment train, for example, sediment pre-filter → Iron Curtain → softener → RO at the kitchen tap.
Annual Maintenance for Private Wells
WA Department of Health recommends private well owners test their water at minimum annually, and twice yearly for arsenic and bacteria. The Idaho Department of Environmental Quality recommends similar. Specific maintenance tasks every well owner should plan for:
- Annually: Test bacteria + nitrate + nitrite. Inspect well cap, casing, and visible plumbing for damage.
- Twice yearly: Test arsenic. The WA DOH recommendation is based on the observation that arsenic levels vary seasonally with groundwater flow.
- Every 5 years: Full panel including TDS, lead, PFOA/PFAS where applicable.
- After major flood events: Test bacteria immediately. Shock-chlorinate per WA DOH protocol if positive.
- After wildfire near the wellhead: Test for VOCs. Wildfires can pull benzene and other VOCs into well systems through damaged plumbing or compromised seals.
- System maintenance: Iron Curtain and softener media should be inspected annually. Filter cartridges replaced on schedule (3–12 months depending on type). UV bulbs replaced annually if installed.
Featured PNW Well-Water Guides
Frequently Asked Questions
Is private well water safer than city water?
It depends entirely on the well and the homeowner. A well-maintained, properly tested PNW well in a low-contamination area is excellent water. A neglected well in an arsenic-prone basalt formation, near agricultural runoff, or with a damaged sanitary cap can deliver contaminants well above EPA limits. The difference is that municipal utilities are tested daily by professionals; private wells are only as safe as the owner makes them.
How often should I shock chlorinate my well?
Only when a coliform test comes back positive, after a flood event, after well work that exposes the casing, or after the well has been off-line for an extended period. Routine shock chlorination every year is not recommended, it stresses pumps and pressure tanks and is not a substitute for fixing the underlying contamination source. WA DOH publishes a step-by-step shock chlorination protocol.
What is the EPA limit on PFOA/PFAS in drinking water?
As of April 2024, the EPA final Maximum Contaminant Level (MCL) is 4.0 parts per trillion (ppt) for PFOA and PFOS individually, and a Hazard Index of 1.0 for mixtures including PFNA, PFHxS, PFBS, and HFPO-DA. This applies to public water systems by 2029. Private wells are not regulated, but the same 4.0 ppt threshold is what Water Guys uses as the action level for recommending RO with PFAS-certified stages.
How do I find out if my well is on a known-contaminated aquifer?
Both Washington and Idaho Departments of Ecology / Environmental Quality publish groundwater contamination maps. WA DOH's Sentry Program is the public-facing query tool for known contamination sites. Idaho DEQ provides similar mapping. Your local health district can also share neighborhood-level contamination history.
Should I test before or after my treatment system?
Both. Pre-treatment testing tells you what to treat for and how to size the system. Post-treatment testing verifies the system is working. We recommend annual post-treatment lab tests for any well-water installation; the lab work runs about $80–$200 and is the only way to confirm contaminant removal in lab-grade ppm/ppb units.
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