If the water from your faucet comes out as a stream of fine bubbles, the faucet has an aerator. If you can't see the aerator on the end of the spout, it's a cache aerator. The name indicates that the aerator is tucked up inside the faucet spout, and if you need to remove it, which you do from time to time, you can't do it with a wrench. The cache aerator is a common feature on Delta faucets, so to complete a basic Delta faucet repair, you need a tool to remove the aerator.
Delta makes a key for removing a Delta faucet aerator, and you can also buy a third-party key that works on most available faucets, including Delta faucets. If you don't have a key, you may, in true DIY style, want to look for an implement you already have that will do the job rather then waiting for a key to be shipped to your door. Several tools and utensils will do the job, but you might not need any of them.
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What Does the Aerator Do?
As the name implies, an aerator oxygenates the water coming from the spout while saving water by reducing flow, and it does this through a very simple mechanism. The reverse side of the aerator, which is the part inside the faucet, is punctuated with many tiny holes. When water is forced through one of them, the pressure increases. The result is that, instead of a languid waterfall from the spout, you get a brisk, invigorating spray.
The flow-restricting holes are protected by a screen, which mineral deposits can collect on and eventually reduce the flow to a trickle. It's easy to clean the screens and, if necessary, the entire aerator, but to do that, you need to remove it.
Things Are Easy If You Have the Key
If you put a mirror under the faucet spout, you'll be able to see that an inset Delta faucet aerator has a series of notches around its outer perimeter. Delta makes a cylindrical plastic tool that fits inside the spout and couples with these notches, allowing you to unscrew the aerator by turning the key.
Third-party manufacturers sell similar keys of different sizes joined in a cross-shaped tool, but the most ingenious key of all is a flat one with two pairs of evenly spaced projections on the ends. This key, manufactured by Zurn, is widely available online and costs less than $2. If you have a faucet with a cache aerator, you need one of these keys.
Remove a Cache Aerator Without a Key
Before you start searching through your drawers to find a flat implement that's just wide enough to fit into the aerator and hook on the notches, try turning the aerator with your fingers. Chances are that the person who installed it didn't have a key either and just tightened it by hand. If you can't turn it, put on a rubber glove to give yourself a better grip and try again.
If a tool becomes necessary, try using a knife from your kitchen drawer. A flat-head screwdriver will also probably work if you wedge the tip into one of the notches and push. Tapping the screwdriver with a hammer will release the grip of mineral deposits that may be binding the aerator.
You can also use a pair of needle-nose pliers to turn a stubborn cache aerator. Open the jaws, hook the tips in the notches on the aerator and spin the aerator counterclockwise.