how many layers do water filters have?

Question:

It depends on what the filter is meant to remove from the water. Most filters are categorized as 2-stage, or 4 stage filters and so on. The differents stages (or layers) all filter different contaminants. A good explanation can be found at http://www.doulton-water.com/understandingwaterfiltration.aspx

Answers:

The filter on the faucet is only a single layer of screen.