§ 705.420. Backflow Prevention Assemblies.

A. 

Any backflow prevention assembly required to protect the facilities listed in Section 705.410(C) shall be of a model or construction approved by the Water Purveyor and the Missouri Department of Natural Resources.

1. 

Air-gap separation to be approved shall be at least twice the diameter of the supply pipe, measured vertically above the top rim of the vessel, but in no case less than one (1) inch.

2. 

A double-check valve assembly or a reduced pressure principle backflow prevention assembly shall be approved by the Water Purveyor, and shall appear on the current "list of approved backflow prevention assemblies" established by the Missouri Department of Natural Resources.

B. 

Existing backflow prevention assemblies approved by the Water Purveyor at the time of installation and properly maintained shall, except for inspection and maintenance requirements, be excluded from the requirements of this Article so long as the Water Purveyor is assured that they will satisfactorily protect the water system. Whenever the existing assembly is moved from its present location, or requires more than minimum maintenance, or when the Water Purveyor finds that the maintenance constitutes a hazard to health, the unit shall be replaced by a backflow prevention assembly meeting the requirements of this Article.

Ord. No. 776 §VII, 3-4-1999