Water Well Types
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Groundwater is one of Missouri’s most vital natural resources. If you just consider public water supplies, more than 94 percent of the 1,191 primary public water supply systems listed in the 2007 Census of Missouri Public Water Systems use groundwater. Combined, they provide water to a population of more than 1.82 million residents, or nearly 36 percent of the 5.07 million residents who receive their water from public water supplies. In addition, there are some 500,000 residents, mostly rural, that are self supplied. Nearly all of them rely on groundwater.
Water well construction has been regulated in Missouri for many years. Public water supplies have been regulated far longer than private water supplies, principally to ensure that the water provided by them meets appropriate water quality standards. Private wells have been regulated since 1985 when the Water Well Drillers Act became law. However, the quality of water produced by private wells is not monitored or regulated by the department.
Department of Natural Resources' regulations determine the type of well that is required for a particular use. Wells producing water for human consumption are either 1) private domestic wells, 2) multiple family wells, 3) non-community public water supply wells, or 4) community public water supply wells. The determination as to which type of well is required is based on the number of service connections, the number of people served, and the length of time during a year the population is served.
Private domestic wells are those that serve from one to not more than three families, provide water to fewer than 25 people on a permanent basis, and produce less than 70 gallons of water per minute. Multiple family wells can serve from four to 14 service connections, but must serve a permanent population of less than 25 people daily at least 60 days each year. Generally, any well serving nine or more single-family dwellings, apartment units, or condominium units, will need to meet community public water supply well specifications because it will likely be serving a permanent population of 25 or more people. Private domestic wells and multiple family wells are considered private wells, and are administered by the Wellhead Protection Section, Division of Geology and Land Survey (in Rolla, phone: 573-368-2165). The construction standards for the different types of private wells vary depending on location. The standards that apply to a private domestic well in northwestern Missouri, for example, are considerably different than what apply to a well in the Ozarks. There are six drilling areas in the state, each having different minimum construction standards. There are also three special areas and four sensitive areas where special rules apply. The rules and regulations pertaining to the construction of private domestic wells, multiple family wells, heat pump wells and monitoring wells are can be found in the department publication "Missouri Well Construction Rules: Private Water Wells, Heat Pump Systems, Pump Installations and Monitoring Wells."
Most private domestic wells and multiple family wells can be constructed by permitted water well contractors without prior contact with the Wellhead Protection Section. However, wells drilled in the special and sensitive areas require differing lengths of casing depending on the exact location of the well. Minimum casing depths for those wells can be obtained from the Wellhead Protection Section. A casing depth form can be downloaded and sent to the Wellhead Protection Section.
The remaining types of wells that provide water for human consumption are considered public water supply wells, and are administered by the Public Drinking Water Branch, Water Protection Program, Division of Environmental Quality in Jefferson City, 573-751-5331. Non-community public water supply wells are those with 15 or more service connections, or those that regularly serve an average of at least 25 individuals daily at least 60 days out of the year. They are not intended to supply a permanent population on a 24-hour per day, year-around basis. Non-community public water supplies are either transient or non-transient systems. The Public Drinking Water Branch can require engineering plans for any public water supply well. However, this requirement may be waived for transient non-community wells provided that the well sites meet the minimum recommended distances from potential contaminant sources. Transient non-community wells are those that serve a changing population such as at a campground, motel, or restaurant. Non-community wells constructed for certain uses such as supplying schools and large businesses that employ more than 25 people and that use the water more than 6 months per year are classified as non-transient, non-community wells. Non-transient, non-community wells must have engineering plans prepared, reviewed and approved before the well can be constructed. The construction standards for non-community public water supply wells can be found in "Standards for Non-Community Public Water Supplies, 1982."
Community public water supply wells are those with 15 or more service connections, or that regularly serve 25 or more people on a year-round basis. Community public water supply wells serve towns, cities, subdivisions, and mobile home parks. They generally serve the same population on a continuous basis, and must be designed by a registered professional engineer. The engineering plans must be reviewed and approved by Public Drinking Water Branch before construction on any regulated part of the supply may begin. The construction standards for community public water supply wells can be found in "Design Guide for Community Water Systems."
The Public Drinking Water Branch must be contacted before construction begins on any public water supply well to determine if it is a non-community or community supply, and if an engineer is required. The Water Resources Center provides casing depth specifications and total depth recommendations for all public water supply wells. Casing depth specifications for non-community wells will not be provided until the Department of Natural Resources’ regional office serving that area has approved the well site. The casing depth form used for private wells can also be used for public water supply wells. However, it should either be faxed to 573-368-2193, or mailed to:
Department of Natural Resources
Water Resources Center
P.O. Box 250
Rolla, MO 65402