Iowa Admin. Code r. 567-49.16
A well cap shall be used on any well not protected by a wellhouse and must seal tightly against the casing to exclude surface water, dirt, insects or any foreign matter from entering the well. The well casing shall terminate at least one foot above the finished grade surface. A split-top sanitary seal may only be used on a well terminating within a wellhouse. Any openings in the cap or seal, such as for pump wiring, water depth measurement, or chemical feed, shall be properly grommeted or sealed, except properly screened and oriented vent openings. There shall be no openings through the well cap except for a factory installed vent, air line chemical feed, and power supply wiring, unless a proposal is submitted to and approved by the administrative authority. To be approved, the proposal must show that any entrance into the well cap is watertight and meets the following conditions: prevents surface water from entering the water supply, is secured in position, is removable with tools only, and is resistant to weathering and corrosion.
Well pump systems that are not under continuous pressure and have no pressure tank may discharge out of the top of the well if all connections are watertight welds or grommeted openings. Venting, heights and other cap requirements shall be met.
Iowa Admin. Code r. 567-49.16