Well water

Short definition

Well water is groundwater drawn from a private well — untreated by any utility before it reaches the tap. If your home is on a private well in WA, you are the de-facto utility: responsible for testing, treatment, and maintenance. WA splits well-water service into Group A systems (15+ connections, DOH-regulated), Group B (2–14 connections, county-regulated), and individual private wells (single-family, not regulated as a public system). Most rural WA homes are individual private wells.

What it is

Groundwater pumped from a well bore drilled into an aquifer. Water enters the well through a screened or open-bottom intake, gets lifted by a well pump into a pressure tank, and supplies the building under steady pressure.

What separates well water from utility water:

• No central treatment. Whatever’s in the aquifer comes to the tap, modified only by whatever treatment you’ve installed at the wellhead or point-of-entry.
• No mandated testing. WA DOH recommends annual coliform testing for private wells; nothing requires it on a single-family individual well.
• Aquifer chemistry varies enormously. Within a few miles, two wells can deliver dramatically different water — one hard and iron-stained, the next soft and acidic.

The three classifications WA uses:

• Group A public water system. 15 or more service connections, or 25+ people 60+ days per year. Regulated by WA DOH Office of Drinking Water under WAC 246-290 with required sampling and reporting.
• Group B public water system. 2–14 connections (and below the Group A thresholds). Regulated by your local health department under WAC 246-291.
• Individual private well. Single-family on its own well. Not regulated as a public water system. The well construction itself is regulated (WAC 173-160, licensed driller); the water quality is the homeowner’s responsibility.

Why it matters to a homeowner

Owning your own water means owning your own water-quality program. Three things to handle on a yearly cycle:

• Test annually for coliform bacteria. A coliform-positive result means the well cap or casing seal is letting surface water reach the aquifer. The fix: shock-chlorinate the well, repair the cap or seal, retest. WA DOH recommends annual testing through a certified laboratory or your county health department.
• Test periodically for the regional risks. Arsenic, nitrate, lead, and uranium each have specific WA regions where they’re more likely. One thorough test (every 3–5 years for stable parameters) tells you what treatment, if any, you need.
• Walk the wellhead twice a year. Look for cracked or unsealed well caps, surface water pooling near the casing, and any pump-house plumbing wear. A $30 well cap replacement is the cheapest contamination prevention you’ll ever do.

When you buy a property with a well, the pre-purchase tests should include coliform (at minimum), nitrate, lead, iron, manganese, hardness, pH, and arsenic if you’re in an arsenic-prone region. The cost is $200–$500 for a comprehensive panel — a small fraction of the price of cleaning up after a contamination surprise.

Common quality issues by region

Different aquifers, different problems:

• Spokane Valley-Rathdrum aquifer (Spokane area): hard water (high calcium / magnesium); softener common.
• Columbia Basin basalt aquifers (much of central WA): iron, manganese, sometimes arsenic; iron filter and arsenic-removal where indicated.
• Lower Yakima Valley (agricultural): nitrate from fertilizer runoff and septic systems; nitrate-removal (anion exchange or RO).
• Hood Canal / Kitsap / Mason alluvium: iron, manganese, sometimes hydrogen sulfide (“rotten egg” smell); iron filter, sometimes shock chlorination.
• Western WA shallow wells in fir/cedar areas: soft, slightly acidic, sometimes tannins (color); pH neutralizer, activated carbon for tannins.
• Parts of Whatcom, Skagit, Klickitat, Kitsap: elevated arsenic in select bedrock wells; iron-based adsorption or RO.

A single panel test will tell you which apply at your specific well. Don’t assume your well’s chemistry from neighbors’ wells without confirming.

Common treatment options

See iron filter, pH neutralizer, water softener, reverse osmosis, and activated carbon filter.

Common failure modes

• Coliform-positive test. Well-cap or casing-seal failure; pulled pump introduced contamination; surface flooding reached the wellhead.
• Sudden taste, color, or odor change. Possible aquifer contamination event; stop drinking, test immediately.
• Iron staining despite a filter. Treatment system undersized, regeneration cycle skipped, or media exhausted.
• Cloudy / milky water. Air entrainment from a worn pump, broken drop pipe, or undersized pressure tank.
• Pinkish-orange residue in toilet bowls. Iron bacteria — common in WA wells; periodic shock chlorination plus filtration.

Common variants and not the same as

• Well water (private) vs. utility water (Group A municipal). Different regulatory framework entirely.
• Group A (15+ connections) vs. Group B (2–14) vs. individual private well (single-family). Different rules, different sampling expectations.
• Drilled well vs. dug well vs. driven well (sand-point). Most modern WA wells are drilled.

Washington note

The legal framework for WA private wells:

• Construction: WAC 173-160 — well construction by a licensed driller; well log filed with WA Department of Ecology.
• Water rights: WA Department of Ecology — single-family domestic use is exempt from water-right permit (RCW 90.44.050) up to 5,000 gallons per day, but exempt status is being interpreted more narrowly in over-appropriated basins.
• Water quality (private wells): Not regulated as a public water system. WA DOH publishes well-water testing guidance and maintains the Drinking Water Tracking System for public systems.
• Group A and Group B: WAC 246-290 and WAC 246-291 respectively — public-system regulation by DOH and local health departments.

For a single-family private well, the practical checklist:

1. Confirm the well log on file with Ecology.
2. Test annually for coliform; one comprehensive panel every 3–5 years.
3. Walk the wellhead twice a year; protect from surface water and contamination.
4. Sample any time taste, odor, or color shifts.
5. At property sale, expect the buyer to want a recent comprehensive test.