Gunk gathering in a faucet? Here’s what to do.

A: You have what’s known as a waterfall faucet, a type designed to send water cascading in a smooth flow over a wide lip. Some waterfall faucets have an open, metal spillway, but yours looks like the brushed nickel version of the Novatto Modern Single Hole Waterfall Vessel Bath Faucet, which directs the water out between two sheets of glass. Home Depot sells it as a Novatto Monroe faucet for $137.59, or $185.05 with a drain assembly.

When people buy the faucet with the drain assembly, they also get a kit for applying Glacier Ice stain guard and sealer to the glass, as well as to the metal parts of the faucet, the sink and the countertop. The kit contains a premoistened towel with enough of the product to treat 35 to 50 square feet, according to the label. The kit also contains a microfiber towel for buffing the stain guard after it dries.

The stain guard keeps the glass clear of mineral deposits and oxidation, said Bob Vander Wall, the owner of Novatto (novattoinc.com). It bonds with silica in the glass, sealing microscopic pores and making the surface hydrophobic. By keeping water from drying on the surface, it prevents the mineral deposits that form when water evaporates and leaves any minerals in it behind. It should also prevent mildew, because a lengthy wet period is needed for that to grow. “The closest relatable thing is Rain-X rain repellent for a window shield,” Vander Wall said. But while Rain-X (rainx.com) rates a five in its ability to make molecular bonds with silica, “ours is a seven,” Vander Wall said. “It makes the glass harder and denser.”

Asked why it isn’t applied at the factory, rather than left as something for customers to do themselves, he said that in a perfect world, it would be done at the factory; however, “the sealer comes from a California manufacturer,” he said. “The faucet is made in China.”

The kit won’t remove deposits that have already formed on the glass, Vander Wall said. For that, he recommended using Glacier Ice Faucet and Sink Restore with Sealer Kit, which contains small bottles of a cleaner and a sealer, plus an applicator sponge and a microfiber towel for the final buffing ($46.99 on Amazon). However, this treatment will work only on exterior parts of your faucet, because the instructions say to rub on the cleaner with the sponge, which is far too bulky to fit between the pieces of glass.

There’s no point in taking apart your faucet, because the glass assembly won’t come apart. Vander Wall suggested using brushes designed for cleaning reusable drinking straws, such as the Hiware Drinking Straw Brush Set ($4.99 on Amazon). The set has brushes in two sizes, the narrowest of which are ⁵/₁₆-inch wide on wands a little over 7 ¹/₂ inches long. Vander Wall said he hasn’t personally tried to clean the faucet, but based on dimensions, the straw brushes should work.

If you can’t scrub away all of the gunk just with mechanical action, you might be able to squirt a diluted bleach solution between the glass using a syringe. The type with blunt-tip needles — sold for applying glue in crafts projects, injecting meat with flavorings or refilling printer ink cartridges — would probably work well. A set of 10 Bstean blunt-tip syringes costs $12.89 on Amazon. The needles range from 20 gauge (equivalent to ¹/₃₂-inch wide) and ½ -inch long to 14 gauge ( ⁵/₆₄-inch wide) and 1½ -inch long. Even the longest needle won’t reach far up between the glass pieces, but the pumping action of the syringe should allow you to squirt much farther in than you could with the other things you’ve tried, especially if you quickly switch to using one of the carburetor brushes to spread the liquid around.

As to whether your well water could be contributing to the problem, the answer is possibly. See the How To column, “Black grit on the faucet is not necessarily a problem,” which published Feb. 24. Well owners should periodically have their water tested for contaminants as well as iron and manganese, which, at high levels, can stain laundry and plumbing fixtures and result in deposits on faucets. Download a list of state-certified testing laboratories from the Maryland Department of the Environment’s Web page about well water.