Does the Avalon A8 effectively filter tap water and improve its taste?

The degree to which a noticeable difference can be detected depends on the quality of your local tap water. The Avalon filters will definitely improve the aesthetics of your water, meaning it will smell better, look cleaner, basically certified to an NASF 42 standard. The other filter is an NASF 53 which eliminates chlorine, lead, rust, and bacteria. For heavily recycled city water, or water with pharmachemical contamination, you may need a higher filter standard.