Short definition

A mineral-spotting or calcified aerator is the WA hard-water version of a clogged aerator: calcium and magnesium carbonates from the water supply precipitate onto the screen and threads, restricting flow and leaving white spotting on the chrome. Vinegar dissolves the scale; thirty minutes and a toothbrush usually fix it. Common in Spokane, parts of the Eastside, and on private wells.

What it is

Hard water carries dissolved calcium and magnesium bicarbonate. As water sits at the spout — between uses — those bicarbonates lose carbon dioxide and precipitate out as solid carbonate scale on whatever surface they touch. Aerator screens are the densest, finest mesh in the spout path, so they catch the precipitate first. Over months or years, the screen turns from open mesh to a calcium-encrusted disk that throttles flow to a trickle.

The visible signs: white crusty deposits around the spout tip, “spotted” chrome that won’t wipe clean with a damp cloth, and a faucet whose flow has slowly weakened over years. The chemistry is simple — calcium carbonate is alkaline, vinegar is acetic acid, and acid dissolves the carbonate.

Why it matters to a homeowner

This is a $1 fix that thousands of WA homeowners pay for as a “low water pressure” service call. If one faucet runs weak and the rest of the house is fine, the answer is almost always a calcified aerator — not a pressure problem.

The procedure: unscrew the aerator (counter-clockwise looking up at the spout, possibly with a strap wrench for stuck chrome), drop it in white vinegar for 15 to 30 minutes, scrub with an old toothbrush, blow out the loosened scale, and reinstall. If the threads are scaled too tightly to unscrew, fill a plastic bag with vinegar, rubber-band it around the whole spout, and let the spout itself soak overnight.

When a plumber’s invoice line reads “descaled aerator” or “limescale removal,” that’s this job. It’s an honest DIY.

Common failure modes

  • Crystalline white scale on the screen. The standard symptom. Vinegar fixes it.
  • Pitted chrome. Different problem — actual chrome corrosion, not cleanable. Replace the aerator.
  • Threads seized to spout. Strap wrench, gentle heat, vinegar bath of the whole spout.
  • Iron-stained aerator (orange or brown). Different mineral entirely, common on private wells. Treatment is iron-removal filtration, not vinegar.

Washington note

Water hardness in WA varies dramatically by source:

  • Seattle (Cedar/Tolt source): very soft, around 30 ppm CaCO3. Aerator scaling is rare.
  • Tacoma: soft, around 40 ppm. Similar.
  • Sammamish Plateau Water: moderate, 75 to 125 ppm. Periodic scaling.
  • Spokane: very hard, 225 to 275 ppm. Aerators may need descaling 1 to 4 times per year.
  • Bellevue and east Lake Washington wells: variable; some neighborhoods on softer surface water, some on harder groundwater.
  • Private wells (Kitsap, rural Pierce, eastern Washington): range from soft to extremely hard depending on the aquifer.

If you’re in Spokane or on a hard-water well, plan on annual aerator and showerhead descaling as routine maintenance. Whole-house water softeners ($1,500 to $3,500 installed) eliminate the chore entirely but add salt cost and water-discharge volume — a real consideration for septic systems.