Wisconsin Administrative Code
Department of Natural Resources
NR 800 - Environmental Protection - Water Supply
Chapter NR 811 - Requirements For The Operation And Design Of Community Water Systems
Subchapter V - Pumping Equipment and Appurtenances
Section NR 811.36 - Well appurtenances

(a) For wells without pitless units, a metal vent pipe shall be installed that terminates in a 24-mesh corrosion resistant screened "U" bend or mushroom cap at least 24 inches above the floor. The vent pipe diameter shall be a minimum of 2 inches for well casings 10 inches in diameter and larger. The department may, on a case-by-case basis, allow smaller diameter well vents on existing installations if water drawdown has not compromised the sanitary seal or require larger diameter well vents for wells with significant water level drawdown. Vent piping shall be welded watertight to the side of the well casing a minimum of 4 inches above the floor and may extend through a concrete pump base or collar where one is present. Alternatively, vent piping may project through a well seal or pump discharge head if the well seal or discharge head is watertight and will facilitate the installation of the vent pipe.

(b) For wells with pitless units, a metal vent pipe shall be installed which terminates in a 24-mesh corrosion resistant screened "U" bend or mushroom cap at least 24 inches above the floor. The pitless unit vent area shall be equal to or greater than the area provided by a 2-inch diameter vent pipe for pitless units 10 inches in diameter or larger. Vent piping shall extend above or be incorporated into the top of the pitless unit or be welded watertight to the side of the pitless unit a minimum of 4 inches above the floor and may extend through a concrete pump base or collar where one is present.

Note: It is recommended that vent installations for pitless units be factory installed to prevent damage to the integrity of factory units and paint systems.

(c) If the well is flowing, the vent shall terminate above the artesian water level or a suitable automatic valve shall be provided.

(a) Provisions shall be made for measurement of static and pumping water levels in the completed well by the use of an electric depth gauge, pressure transducer or an air line attached to the pump column and an altitude gauge.

(b) The installation shall be constructed to prevent entrance of foreign material.

(c) Air lines may not be installed through vent pipes unless justified when modifications are being made to existing installations, the minimum 2-inch diameter vent pipe area is maintained where applicable, and the specific approval of the department is obtained.