A. Location.
1. The source of supply shall be from a water-bearing formation not less than 20 feet from the ground surface and from a formation which is not subject to pollution. A yield of 5 gallons per minute per family is desirable.
2. Wells shall be located so as to be free from surface flooding.
3. The location shall be at a point higher in elevation than potential subsurface pollution sources. The following minimum horizontal distances will be maintained:
Potential Pollution Source | Minimum Distance |
Storm drains | 25 feet |
Sewer or waste drains: | |
Cast iron or equal | 10 feet |
All other materials | 50 feet |
Septic tanks | 50 feet |
Subsurface sewage disposal fields, pits, cesspools, etc. | 100 feet |
B. Construction.
1. Casing:
a. The well shall have a water-tight casing of steel, wrought iron or other approved material.
b. The casing shall be carried into the bedrock or other impervious strata a minimum of 5 feet. In no instances shall there be less than 20 feet of casing installed below the surface.
2. Grouting: An annular space between the well casing and the earth formation shall be completely filled with impervious cement grout or equivalent sealing material.
a. For internal pressure grouting the annular space shall be at least 1 inch greater than the casing radius.
b. For external pressure grouting the annular space shall be at least 2 inches greater than the casing radius.
c. The grout shall extend down to the top of the water-bearing formation, bedrock, impervious strata or otherwise to a depth of at least 20 feet.
3. Screen: A screen of the appropriate type and size may be desirable to exclude solid particles.
4. Pump Installation: Installation of the pump may be either at the surface or below the surface.
a. All types of installations shall be appropriately drained and water-tight so as to preclude contamination by surface and subsurface water.
b. For below the surface installations a pitless installation employing a water-tight pitless adapter is preferred to a pit installation so as to preclude contamination by surface and subsurface water.
c. Pit installations shall be adequately ventilated.
d. The pump suction opening shall be placed at least 2 feet below the maximum draw down of the water in the well.
5. Storage Capacity: The size of the pressure tank needed is somewhat dependent upon the well yield. A capacity of 40 gallons per living unit shall generally be required.
C. Backflow Disinfection, and Quality.
1. Every potable water distributing pipe shall be protected against backflow from any plumbing fixture or other piece of equipment or appliance capable of affecting the quality of the potable water by having the outlet end from which the water flows spaced a minimum distance of twice the diameter of the water supply pipe above the flood level rim of the receptacle into which the potable water flows.
2. Where it is not practicable to provide this minimum air gap, the connection to the fixture, equipment, or appliance shall be equipped with backflow preventor assembly of an approved type.
3. Following construction, alteration, maintenance, or repair of an individual water supply system, the well should be pumped continuously until water discharged is clear. The well, pump, piping system, and other fixtures, shall be filled with water containing a concentration of not less than 50 parts per million of available chlorine for a period of at least 12 hours. Other disinfectant concentrations and time intervals which are known to be equally effective may be used.
4. After flushing the disinfected system, a water sample should be taken for laboratory examination. The laboratory examination should determine the safety and suitabilty of the water for domestic use. If the laboratory analysis shows that the water is not suitable for domestic use, treatment to render the water safe for use may be feasible.