What Is a Well Screen Tool?

Functions

• A well screen serves more than one purpose. Its primary function is to allow water to flow into the hollow well while preventing sand, gravel and rock from entering. A well screen is a cylindrical sheet wrapped around the wall at the base of the well. The slots permeating the sheet let water in and keep ground matter out. Its secondary function is to help support the moist, and often unstable, walls of the well and to prevent them from caving in.

Types

• Well screens are classified by the width of their openings. For example, a well screen with an individual opening measuring 0.1 inch is a number 10 slot screen. Screens can be made of metal or PVC. They can be wire mesh woven around metal rods or PVC pipes with holes or slots drilled into them. Different types of screens have differing levels of efficiency. Deciding which type of screen to use depends on a number of factors including cost, ease of installation and the type of well.

Installation

• Installers mechanically lower well screens into wells and open them up to press them against the walls of the borehole and against the aquifer. Installers sometimes add filter packs between a well screen and the aquifer. This barrier provides additional filtration.