Geological Survey Program fact sheet
Missouri Geological Survey Director: Carey Bridges, RG

What is the law that regulates water wells?

Missouri Law Sections 256.600 to 256.640 RSMo sets minimum construction standards for wells and requires drillers and pump installers to obtain permits to operate in Missouri. The law protects groundwater through proper well construction and plugging as specified in the Missouri Well Construction Rules

Whom does the law affect?

Any person who owns an active or abandoned well, and any person who drills or repairs wells or installs pumps.

When was the law passed and when did the rules take effect?

The bill was signed into law August 1985, and the rules became effective July 31, 1987.

Does the law apply to wells constructed before July 1987? 

Yes, but only concerning the way in which these wells are plugged after they no longer are needed or if the well is deemed to be a threat to groundwater. Pre-law wells currently in use are exempt from the rules. If a pre-law well undergoes major reconstruction (such as deepening or liner installation), then the pre-law well loses its exemption and the rules apply.

To which type of well does the law apply?

All wells drilled after July 31, 1987, must be reported by the driller when completed. The construction, reconstruction and plugging standards specified in the rules apply to domestic, multi-family, high yield, monitoring and heat pump (geothermal) wells. Public water wells are regulated by the Public Water Drinking Branch in conjunction with the Well Installation section.

What are my responsibilities as a well owner with respect to the law?

Potential well owners are responsible for finding a permitted driller to construct or reconstruct their well. The department maintains contact information for all permitted drillers and pump installers. When new wells are completed, owners must pay a processing fee. This fee is for the cost of review and certification of your well. The department will maintain your well information indefinitely. This information is valuable to help evaluate and provide technical advice in case your well develops water quality issues. You may view your well information online at GeoSTRAT.   

Who administers the law?

The Missouri Geological Survey administers the Well Drillers’ Law. The mailing address is PO Box 250, Rolla, MO 65402-0250. The physical address is 111 Fairgrounds Road, Rolla, MO 65401-2909.

Do other states have a similar law?

About 40 other states have a law regulating water well construction.

Is my tax money being used to implement the law? Where does the money from the fees go?

The Well Installation section is fee-supported. Money collected for permit fees and well certification and registration fees is used to administer the law.

Who can give advice about the law?

The Well Installation section is the best source of information about the law.

How many wells are drilled in the state each year?

About 6,000 to 10,000 new wells are drilled each year in Missouri. These include water wells, heat pump wells, monitoring wells and mineral test holes.

Does everyone need a permit who drills a well?

Well drillers and pump installers who charge for their services must have a permit to construct a well. Issuing permits to well drillers and pump installers establishes a minimum standard of competency and enables the department to enforce minimum construction standards. Landowners who drill their own well and/or install their own pump are exempt from permit requirements, but must adhere to all other sections of the rules.

How can I tell whether my driller is permitted?

Permit numbers should be affixed to the well drilling equipment. To ensure a permit is current, you can ask to see their permit card for an expiration date, call the Well Installation section at 573-368-2165.

How often are driller and pump installer permits reviewed?

Permits are reviewed annually for renewal, or when specific incidents occur that warrant immediate attention.

What is the most critical part of the well? Why is this so important?

The proper amount of casing and a good grout seal around the casing are critical to protect groundwater and provide safe drinking water. Casing is an impervious, durable pipe used to prevent soil or loose rock from caving into the well bore. The grout seal is used to prevent surface drainage of undesirable fluids from entering the well.

How much casing does my well need?

The amount of casing required for each well varies, dependent on the geology of the area where you live. Thirteen drillings areas are defined in the rules. These drilling areas are based on geologic conditions, groundwater hydrology, water quality and drilling conditions.

What can I do to be sure that my well is constructed properly?

Contact the Well Installation section at 573-368-2165 before your well is drilled to discuss what to ask the driller and what to look for while your well is being constructed. If your well was drilled after 1987, please contact the section to find out if your well meets minimum construction standards. 

From what sources can my well be contaminated?

Septic tanks, lagoons, feed lots and unplugged abandoned wells are common sources of contamination to wells. 

Can I tell whether my well is contaminated by the water’s taste or smell?

If your water has an odd taste or order, you should have your water tested. However, your water may be contaminated even though it doesn’t have a bad odor or taste.

How often should I have my water tested? Who should test it?

It is recommended to test your water annually for bacteriological contaminants, and test for heavy metals every three years. The results of the analysis will establish a baseline. Private laboratories will test the water quality of a well as will the Missouri Department of Health and Senior Services. Contact your local county health office for sampling instruction and containers.

Can contaminated wells be repaired?

Most contaminated wells can be repaired. However, the type of contaminant, the source of the contamination and geology may make repair more costly than drilling a new well.  

Can my neighbors’ well contaminate mine?  

Yes. The groundwater is always moving. A neighbor’s well can contaminate yours if the groundwater gradient through water-bearing zones or aquifers is from their property to yours.  

Disinfecting your water well?

The department has both a fact sheet, Disinfecting Your Water Well - PUB2733, and a video that provide step-by-step instructions for disinfecting water wells. 

What does the presence of coliform bacteria indicate?

The presence of coliform bacteria in your well water indicates water contaminated by organic material has entered your well. If coliform bacteria are present, E. coli bacteria will be tested for. The presence of E. coli bacteria is a serious health concern. If E. coli bacteria are present, the well should be disinfected immediately and retested to make certain the well water is clear of the contaminant before drinking or using the water for other purposes.

Why are there different construction requirements for different types of wells?

Construction requirements are based on well yield, use of well, (i.e., single family use, multi-family use, public use) and the region in which your well is located. Geology varies greatly throughout the state and often affects construction requirements.

How many homes can use the same domestic well?  

Three single family residences may use one domestic well. A multi-family well may serve three to eight residences. Multi-family wells have more stringent minimum construction standards than do domestic wells.  

Am I liable if my well contaminates the groundwater?

Yes, you may be liable if your well contaminates the groundwater, especially if willful negligence is proven in court.  

What is the proper procedure to plug an abandon well?

The correct way to plug a well varies. It depends on the type of the well, casing depth, and total depth of the well. A department brochure is available that explains the process of plugging a well. A full-length grout plug using approved grout materials always is the best way to plug any well.  

What is a water well report?

A water well report is a form that is completed and provided to the department by the driller. The driller attests the well is constructed according to the rules by signing the report and filing it with the Well Installation section in Rolla, within 60 days of the date your well was completed. The fee for filing a well report for certification is paid by the well owner, and collected by the driller and provided when the report is filed.

Who certifies my well? How is the state involved?

The driller reports the construction of the well by completing the water well report. If the well is constructed properly, the Well Installation section will issue a certification number, which is mailed to the well owner.

How can I get a copy of the Rules and Regulations?

The Missouri Secretary of State’s office provides the Well Installation rules and regulations online. 

Are there setback requirements for locating a new well site?

Yes. Setback distances about the location of the water well in relation to contaminant sources are covered in the regulations in Chapter 3. Contaminant sources include, but are not limited to: septic tanks, lagoons, unplugged wells, cemeteries, feed lots and drain fields.

Nothing in this document may be used to implement any enforcement action or levy any penalty unless promulgated by rule under chapter 536 or authorized by statute.

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