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Environmental Health Division
Isolation Distances From a Water-Supply Well
Minnesota Rules, Chapter 4725
Rules Relating to Wells and Borings
Effective date: August 4, 2008
The isolation distances below are from Minnesota Rules, chapter 4725. Distances must be measured horizontally from the water-supply well. Minnesota Statutes, section 103I.205, subdivision 6, prohibits constructing, placing, or installing an actual or potential contaminant source from a well that is less than the minimum distance prescribed by rule. The minimum isolation distance must be maintained between a new well and a contamination source, even if the contamination source is no longer in use. An isolation distance is not required if the contamination source and any related contaminated soil have been removed. Additional information and explanations can be found in the Rules Handbook, A Guide to the Rules Relating to Wells and Borings, or by contacting the Well Management Section.
If you have questions about isolation distances not listed here, please contact the Minnesota Department of Health Well Management Section.
| Absorption area of a soil dispersal system | ||||
| average flow greater than 10,000 gallons/day | 300 | feet1 | ||
| serving a facility handling infectious or pathological wastes | 150 | feet1 | ||
| average flow 10,000 gallons/day or less | 50 | feet1 | ||
| Agricultural chemical | ||||
| tank or container with 25 gallons or more or 100 pounds or more dry weight, or equipment filling or cleaning area without safeguards | 150 | feet | ||
| storage or equipment filling or cleaning area with safeguards | 100 | feet | ||
| storage or equipment filling or cleaning area with safeguards and roofed | 50 | feet | ||
| buried piping | 50 | feet | ||
| multiple tanks or containers for residential retail sale or use, no single tank or container exceeding, but aggregate volume exceeding 56 gallons or 100 pounds dry weight | 50 | feet | ||
| Anhydrous ammonia tank | 50 | feet | ||
| Animal | ||||
| feedlot, unroofed, 300 or more animal units | 100 | feet1 | ||
| feedlot, more than 1.0, but less than 300 animal units | 50 | feet1 | ||
| building or poultry building, including a horse riding area, more than 1.0 animal unit | 50 | feet1 | ||
| rendering plant | 50 | feet | ||
| feeding or watering area within a pasture, more than 1.0 animal unit | 50 | feet1 | ||
| area to bury more than one animal unit | 50 | feet | ||
| building, feedlot, confinement area, or kennel, 0.1 to 1.0 animal unit | 20 | feet1,2 | ||
| Building, building projection, deck, overhang, permanent structure | 3 | feet3 | ||
| Cesspool | 75 | feet1 | ||
| Cistern or reservoir, buried, nonpressurized water supply | 20 | feet | ||
| Commercial compost site | 50 | feet | ||
| Construction or demolition debris disposal area | 50 | feet1 | ||
| Cooling water pond, industrial | 50 | feet1 | ||
| Deicing chemicals, bulk road | 50 | feet1 | ||
| Drainfield (see Absorption area) | ||||
| Dry well (sewage) | 75 | feet1 | ||
| Electric transmission line | 10 | feet4 | ||
| Electrical transformer storage area, oil-filled | 50 | feet | ||
| Elevator boring, not conforming to rule | 50 | feet | ||
| conforming to rule | 20 | feet | ||
| Fertilizer chemigation tank, safeguarded, from irrigation well only | 20 | feet5 | ||
| Floor drain, grate, or trough | ||||
| connected to a buried sewer | 50 | feet | ||
| if buried sewer is air-tested, approved materials, serving one building, or two or less single-family residences | 20 | feet2 | ||
| Frost-proof yard hydrant or discharge of a frost-proof hydrant draining into the soil, | ||||
| fire hydrant or flushing hydrant | 10 | feet | ||
| Gas (flammable or volatile) pipe | 10 | feet4 | ||
| Grave or mausoleum | 50 | feet | ||
| Gravel pocket or French drain for clear water drainage | 20 | feet | ||
| Gray-water dispersal area | 50 | feet1 | ||
| Hazardous substance | ||||
| tank or container, above ground or underground, 56 gallons or more, or 100 pounds or more dry weight, without safeguards | 150 | feet | ||
| tank or container, above ground or underground, 56 gallons or more, or 100 pounds or more dry weight with safeguards | 100 | feet | ||
| buried piping | 50 | feet | ||
| multiple storage tanks or containers for residential retail sale or use, no single tank or container exceeding 56 gallons or 100 pounds, but aggregate volume exceeding | 50 | feet | ||
| Horizontal ground source closed loop heat exchanger buried piping | 50 | feet | ||
| Horizontal ground source closed loop heat exchanger buried piping and horizontal piping, approved materials and heat transfer fluid | 10 | feet2 | ||
| Household solid waste disposal area, single residence | 50 | feet1 | ||
| Interceptor, including a flammable waste or sediment | 50 | feet | ||
| Land spreading area for sewage, septage, or sludge | 50 | feet1 | ||
| Landfill or dump, mixed municipal solid waste from multiple persons | 300 | feet1 | ||
| Landfill, permitted demolition debris | 300 | feet1 | ||
| Leaching pit | 75 | feet1 | ||
| Liquid propane (LP) tank | 10 | feet4 | ||
| Manure (liquid) storage basin or lagoon | ||||
| unpermitted or noncertified | 300 | feet1 | ||
| approved earthen liner | 150 | feet1 | ||
| approved concrete or composite liner | 100 | feet1 | ||
| Manure (solid) storage area, not covered with a roof | 100 | feet1 | ||
| Ordinary high water level of a stream, river, pond, storm water retention pond, lake, or reservoir | 35 | feet2 | ||
| Petroleum | ||||
| tank or container, 1,100 gallons or more, without safeguards | 150 | feet | ||
| tank or container, 1,100 gallons or more, with safeguards | 100 | feet | ||
| tank or container, buried, between 56 and 1,100 gallons | 50 | feet | ||
| tank or container, not buried, between 56 and 1,100 gallons | 20 | feet6 | ||
| buried piping | 50 | feet | ||
| Petroleum or crude oil pipeline to a refinery or distribution center | 100 | feet | ||
| Pit or unfilled space more than four feet in depth | 20 | feet | ||
| Pollutant or contaminant that may drain into the soil | 50 | feet1 | ||
| Privy, nonportable | 50 | feet1 | ||
| portable (privy) or toilet | 20 | feet2 | ||
| Sand filter, watertight; peat filter; or constructed wetland | 50 | feet | ||
| Scrap yard | 50 | feet | ||
| Seepage pit | 75 | feet1 | ||
| Septic tank | 50 | feet | ||
| Sewage holding tank, watertight | 50 | feet | ||
| Sewage sump | ||||
| capacity 100 gallons or more | 50 | feet | ||
| capacity less than 100 gallons, tested, conforming to rule | 20 | feet2 | ||
| Sewage treatment device, watertight | 50 | feet | ||
| Sewer, buried | ||||
| collector, municipal, serving a facility handling infectious or pathological wastes, open-jointed or unapproved materials | 50 | feet | ||
| approved materials, tested, serving one building, or two or less single-family residences | 20 | feet2 | ||
| Solid waste transfer station | 50 | feet | ||
| Storm water drain pipe, 8 inches or greater in diameter | 20 | feet2 | ||
| Swimming pool, in-ground | 20 | feet | ||
| Unused, unsealed well or boring | 50 | feet | ||
| Vertical heat exchanger (vertical) piping, conforming to rule | 35 | feet2 | ||
| horizontal piping conforming to rule | 10 | feet2 | ||
| Wastewater rapid infiltration basin, municipal or industrial | 300 | feet1 | ||
| Wastewater spray irrigation area, municipal or industrial | 150 | feet1 | ||
| Wastewater stabilization pond | ||||
| municipal, 500 or more gallons/acre/day of leakage | 300 | feet1 | ||
| municipal, less than 500 gallons/acre/day of leakage | 150 | feet1 | ||
| industrial | 150 | feet1 | ||
| Wastewater treatment unit tanks, vessels and components (Package plant) | 100 | feet | ||
| Water treatment backwash disposal area | 50 | feet1 | ||
| Water treatment backwash holding basin, reclaim basin, or surge tank | ||||
| with a direct sewer connection | 50 | feet | ||
| with a backflow protected sewer connection | 20 | feet | ||
|
Additional Isolation Distances For Community Public Water-Supply Wells |
||||
| Highest water or flood level | 50 | feet | ||
| Property line, unless legally controlled through an easement | 50 | feet | ||
| 1 | A sensitive water-supply well must be located at least twice the indicated distance. A sensitive water-supply well is a well with less than 50 feet of watertight casing, and which is not cased below a confining layer or confining materials of at least 10 feet in thickness. |
| 2 | A community public water-supply well must be a minimum of 50 feet from this contamination source. |
| 3 | A well or boring may not be constructed inside a building except as provided for by Minnesota Rules, part 4725.2175. |
| 4 | A well or boring may be located between 5 and 10 feet of an electric transmission line, gas pipe or LP tank if the well or boring is placarded, and work is not performed on the well or boring unless the electric line is deenergized and grounded or shielded, and the LP tank does not contain flammable gas. |
| 5 | The 20-foot distance applies only to an irrigation well and a fertilizer chemigation supply tank meeting the requirements of Minnesota Rules, chapter 1505. |
| 6 | A community public water-supply well must be a minimum of 50 feet from a petroleum tank or container with a capacity between 56 and 1,100 gallons, unless the tank or container is used to fuel emergency pumping equipment and is located in a room or building separate from the community well; and is of double-wall construction with leak detection between walls; or is protected with secondary containment. |
Print Information Sheet
Isolation Distances From a Water-Supply Well (PDF)
Questions
Well Management Section
651-201-4600 or 800-383-9808
health.wells@state.mn.us
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