Who Regulates Water Wells in Missouri? - PUB4001

The Missouri Department of Natural Resources is the regulatory authority for constructing, maintaining and plugging water wells in Missouri. The department’s Missouri Geological Survey, Well Installation Section (WIS) is responsible for certifying all water wells according to Missouri Revised Statutes section 256.614.1, RSMo. Water wells that serve the public and meet the definition of a public water supply, as defined in section 640.100, RSMo, are regulated by the department's Water Protection Program, Public Drinking Water Branch (PDWB). Water wells regulated by PDWB require construction authorization before drilling. This fact sheet is intended to help well owners, developers and well and pump installation contractors determine whether a proposed well requires pre-construction authorization.

Jurisdiction 

WIS and the PDWB work closely together to protect Missouri groundwater resources and the water delivered to consumers. WIS is responsible for certifying water wells, monitoring wells, heat pump wells, test holes and pump installations according to section 256.614.1, RSMo. WIS also oversees the water well drilling industry, which includes permitting well and pump installation contractors along with registering equipment and vehicles, such as drill rigs and pump trucks.

The PDWB reviews and approves construction permit applications for drinking water wells that serve, or will serve, a public water system, according to section 640.100, RSMo. That statute defines a public water system as “a system for the provision to the public of water for human consumption through pipes or other constructed conveyances, if such system has at least 15 service connections or regularly serves an average of at least 25 individuals daily, at least 60 days per calendar year.” This includes subdivisions with multiple wells, unless each lot or tract is served by a private well with no interconnection to a distribution system and the wells are not owned or operated by a common continuing operating authority. The PDWB also monitors public water systems according to national primary drinking water standards, certifying drinking water operators, issuing construction authorization permits and permits to dispense water. The PDWB additionally provides technical, managerial and financial assistance to Missouri’s public water systems.

Types of Wells 

Private Wells 

Private water wells are wells that do not serve a public water supply, or subdivision, as defined in Missouri Code of State Regulations 10 CSR 60-2, Definitions. Private water wells fall under one of the following categories:

1. Domestic Well - A domestic well is a private water supply well equipped with a pump that does not have the capacity to produce 70 gallons or more of water per minute at the surface and has three or fewer service connections as defined in 10 CSR 23-1.010(19)(D), Definitions.
2. Multi-family Well - A multi-family water well is a private water supply well that is equipped with a pump that does not have the capacity to produce 70 gallons per minute at the surface, has more than three service connections and does not supply water to a public water system as defined in section 640.102, RSMo.
3. High-yield Well - A high-yield well is a well that is equipped with a pump that has the capacity to produce 70 or more gallons of water per minute to the surface and does not supply water to a public water system. Often, these wells are used to irrigate agricultural crops but can also supply water for other domestic or industrial uses. 

Construction requirements for private wells, including methods and materials, vary between category and location. Requirements for domestic, multi-family and high-yield wells are found in 10 CSR 23-3, Water Well Construction Code.

Public Water Systems 

A public water system provides water, through pipes or other constructed conveyances, for human consumption that:

• Provides at least 15 service connections or
• Regularly serves an average of at least 25 individuals daily, at least 60 days per calendar year. 

A public water system is further classified into one of the following categories, depending on whether they serve the same people year-round or on an occasional basis:

1. Community Water System – A public water system that serves at least 15 service connections and is operated on a year-round basis or regularly serves at least twenty-five residents on a year-round basis. A community water system may be composed of multiple water wells that have less than 15 connections on each well, but when combined with other wells owned or operated and financed by the same entity, have more than 15 connections or serve 25 residents on a year-round basis. Some examples of a community water system are cities, subdivisions, mobile home parks, residential care homes, or anywhere where people live and sleep.
2. Nontransient Noncommunity Water System – A public water system that is not a community system and serves at least 25 of the same persons over six months per year. Some examples of a nontransient noncommunity water system are schools, daycares, factories or other businesses where the same large group of people attend on a regular basis.
3. Transient Noncommunity Water System – A public water system that is not a community water system, which has at least 15 service connections or regularly serves an average of at least 25 individuals daily at least 60 days out of the year and does not serve the same population on a regular basis. Some examples of a transient noncommunity water system are campgrounds, restaurants, charitable or benevolent organizations, and convenience stores. 

Human consumption includes water for drinking and cooking as well as bathing, food preparation and handwashing. The water source may be groundwater with associated wells, a surface water intake system, or a combination of the two. The department recommends persons proposing to construct or modify a subdivision, residential housing development, apartment, condominium, manufactured home park or motel use the populations per service connection in the department’s Minimum Design Standards for Missouri Community Water Systems - PUB2489 to determine if a public well is warranted for developments with fewer than 15 service connections.

Populations Per Service Connection

Construction Authorization for Public Wells 

Public water systems must receive written approval from the PDWB before constructing or altering a public well, unless the system meets the charitable and benevolent organization exemptions in section 640.116, RSMo. Anyone proposing to install a public well must contact the department’s regional office for a well site survey. The survey ensures the proposed well meets minimum isolation, or setback, distances from known or potential contaminant sources, including, but not limited to, septic tanks, sanitary sewer lines, and landfills. 

The public water system must obtain an estimated casing depth letter from the department's Missouri Geological Survey, Water Resources Center before applying for construction authorization with PDWB. The estimated casing depth for the well is set to minimize its possible impacts to nearby wells and maximize the likelihood the well can produce the amount of water needed. There is no fee for these services. Failure to obtain construction authorization from the department may result in approval delays and possibly the owner having to properly plug the well and drill a new one according to 10 CSR 60-3, Permits. More information about public well standards and the construction authorization process are available in the department’s Minimum Design Standards for Missouri Community Water Systems - PUB2489 and the Standards for Non-community Public Water Supplies - PUB0979.

If you need help determining if your proposed water well serves a public water system and therefore needs prior approval, contact the Public Drinking Water Branch.