White crusty buildup on faucets and showerheads is mineral scale, mostly calcium and magnesium carbonate left behind when hard water evaporates. It won’t hurt you, but it does look bad and, over time, it can clog aerators and restrict flow. The good news: most of it comes off with things you already have at home.
What Hard Water Scale Actually Is
Your water picks up dissolved minerals as it moves through rock and soil. The Bay Area and most of Central California draw from sources with moderate to high hardness. Hardness varies widely depending on whether your utility pulls from surface water or groundwater and how much blending they do. When that water sits on a chrome faucet or a polished nickel showerhead and evaporates, the minerals stay put. Repeat that a few hundred times and you get the white, chalky crust people call hard water stains or limescale.
It’s not the same as soap scum, though they often appear together. Soap scum is a fatty acid residue that grabs onto the scale and turns yellowish-gray. The removal method is similar, but the underlying cause is different.
Removal Methods That Actually Work
White vinegar (undiluted)
This is the cheapest and most effective first move. Distilled white vinegar is mildly acidic and dissolves calcium carbonate without scratching most finishes.
For a faucet aerator: unscrew it, drop it in a small bowl of straight vinegar, and let it soak for 30 to 60 minutes. Heavy buildup may need a few hours. Rinse, reassemble.
For a showerhead: fill a zip-lock bag with vinegar, submerge the showerhead face in it, and secure the bag with a rubber band around the neck. Leave it for a couple of hours or overnight for standard chrome or stainless finishes. If your showerhead has a brushed nickel, brass, or specialty coated finish, limit the soak to 30 to 60 minutes because extended acid exposure can affect those surfaces. In the morning, run hot water through it for a minute to flush the loosened scale.
For faucet handles and spout exteriors: soak a paper towel in vinegar, wrap it around the buildup, and tape it in place for 20 to 30 minutes. The towel holds the vinegar against the surface.
Lemon juice
Works the same way as vinegar (citric acid vs. acetic acid) and smells better. It’s a gentler option on delicate or specialty finishes where you want to be cautious. Squeeze fresh lemon or use bottled 100% lemon juice.
CLR or similar descalers
For scale that vinegar didn’t fully remove, a product like CLR (Calcium, Lime, Rust) can be effective. Check the label carefully and follow the directions. Most call for dilution and a brief contact time, then a thorough rinse. CLR’s own instructions say do not leave it on any surface longer than two minutes. Do not use it on natural stone, colored grout, brass, copper, aluminum, or painted and coated surfaces. Check your specific fixture manufacturer’s care guide before using any acid-based descaler, since some finishes are more sensitive than others.
What to avoid
Steel wool, scouring pads, and abrasive powder cleaners will scratch the finish permanently. Bleach doesn’t dissolve minerals at all. “Magic eraser” type pads are micro-abrasive and will dull polished surfaces over time.
When DIY Cleaning Isn’t Enough
Sometimes the scale is a symptom of something deeper.
If you’ve cleaned the aerator and flow is still weak, the buildup may be inside the supply lines or the valve cartridge. Many major brands make replacement cartridges that are DIY-accessible if you’re comfortable shutting off supply valves, but if the shut-off valve itself is stiff or won’t fully close, stop and call a plumber. Forcing a corroded valve is a good way to create a much bigger problem.
If you’re seeing orange or rust-colored staining alongside the white scale, that’s a different issue. Orange staining usually means iron in the water or oxidation inside an older galvanized pipe. That’s worth investigating by a licensed plumber, not just wiping down.
Flaking, pitting, or chalky discoloration on the fixture finish itself (not just buildup on top of it) means the finish is breaking down. Kohler’s PVD finishes tend to be durable and this is less common, but on older chrome-plated brass it can happen. Refinishing or replacing the fixture is the fix, not cleaning.
What the Scale Tells You About Your Water
Moderate scale on faucets means your water is moderately hard, which is normal in most California homes. Heavy scale that returns within weeks of cleaning, or scale in unusual places like inside toilet tanks, suggests your water is on the harder end of the spectrum.
A plumber can run a basic water hardness test and tell you whether a whole-house water softener or a dedicated scale inhibitor makes sense for your situation. A salt-based softener replaces calcium and magnesium with sodium ions and nearly eliminates scale. Salt-free conditioners use a different process to reduce how readily minerals deposit on surfaces, but the minerals stay in the water. Each has trade-offs worth discussing with someone who knows your specific supply, pipe age, and appliance mix.
When to Call a Licensed Plumber
Get a plumber involved if:
- The aerator or showerhead is clogged repeatedly, even after cleaning (possible buildup inside pipes or a failing cartridge)
- You find orange or rust staining, which may mean corroding galvanized pipes
- Any shut-off valve under the sink or behind the toilet won’t turn easily
- You’re considering a water softener or whole-house filtration system (sizing and installation affect water pressure and appliances)
- There’s visible corrosion, pinhole staining, or mineral deposits on exposed pipe joints
In California, plumbing work on supply lines and fixtures requires a licensed contractor. You can verify any plumber’s license at cslb.ca.gov before they start work. Put the license number in and confirm it’s current and in good standing. It takes 30 seconds and protects you.
Cleaning the visible scale yourself is reasonable and usually works. Everything behind the wall or under the floor belongs to someone with a license.