I have a Kohler purist faucet in my bathroom -- solid brass everything, chrome plated. I have had to replace the handles once before due to corrosion at the base of the top handle section. These are corroding again. Also, new, the steel retaining washer that clamps the center faucet to the sink corroded away entirely (turned to dust when I touched it)

I'm trying to figure out what I can change to minimize galvanic couples here. Should I swap out my supply tubing with non-metal reinforced, to isolate the valves from the supply? Or is a few drops of standing water at the interface between the brass and chrome enough to cause corrosion at the handle? The hardware underneath the sink looks like some sort of plated steel standoff. I think the large nut is brass, though I can't tell.

For the steel clamp washer, do I need to add a nonmetallic gasket between the nut and washer to try to keep is isolated? Should I install some rubber tube or Teflon tape around the threaded faucet stem where it would come in context with the steel washer, to try to isolate it? The center stem has a threaded section where a (brass?) nut was tightened against a steel clamp washer, then has a brass T with plastic tubing to the hot and cold valves. There is also a chrome drain lift, which connects to what looks like a steel extension before connecting to the brass drain trip.

Or, is this a problem that I need to putty better between sink and up top, to keep moisture from seeping below?

Here is corrosion around the valve handles: Corrosion around handle

Here is where the steel clamp washer once lived (under sink) before turning to dust Spot where steel clamp washer once lived

Close up of supply line setup Supply lines

Center faucet stackup underside: Underside of center faucet

Detail of valve to sink connection Underside of valve

  • It's common for the steel clamp washers to eventually do that. It looks like there's some corrosion in some spots on the faucet handle, like where the horizontal handle bar meets the vertical portion of the handle. But the disk at the bottom of the handle (center of the picture) looks like mechanical damage, like it got chewed up by vice grips.
    – fixer1234
    Commented Dec 31, 2022 at 23:29
  • If you think you have galvanic currents doing that, ground the pipes
    – Traveler
    Commented Jan 1, 2023 at 0:39
  • @fixer1234 it looks mechanical, but is in fact just corrosion. I am guessing maybe where the two parts meet, it got scratched, and since water wants to sort of seep in there it is always damp.
    – JonB
    Commented Jan 1, 2023 at 6:18
  • 1
    Plain steel has no proper place in any part of a bathroom fixture, the washer should have been stainless steel or brass. There are innumerable varieties of brass, and some are far more susceptible to corrosion than others. Horrible corrosion of "brass" and pot metal alloys used in fixtures sourced from China has been a common experience.
    – kreemoweet
    Commented Jan 1, 2023 at 6:38
  • This may be worth investigating. There was a time when imported drywall from China was found to be corroding faucets and such in homes. Do a search, perhaps some work was done or the house was built during the time this was being used. I just used the search term "chinese drywall imported" and got some pertinent info.
    – Jack
    Commented Jan 1, 2023 at 17:34

1 Answer 1


If you are using a cleaning product that contains ammonia, such as Windex, this can contribute to corrosion of brass. Ammonia aggressively attacks brass and creates stress fissures that promote further corrosion.

This is especially true if ammonia remains in contact for a time. For example, if you spray the faucet handle, some cleaning product may seep under the handle and remain there.

Although brass is usually considered corrosion-resistant, chrome plated brass consists of brass, then a coating of copper, then a coating of nickel, and finally chromium on top. The first coating, copper, a fairly reactive metal, can be the first point of failure if there are any scratches or imperfections. Once corrosion begins under the chromium layer, corrosion can proceed fairly rapidly.

  • Scouring powders with bleach and other harsh chemicals are commonly used in bathrooms, and they take their toll.
    – kreemoweet
    Commented Jan 1, 2023 at 6:42

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