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Well Management Section

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health.wells@state.mn.us

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.

Isolation Distances From a Water-Supply Well (PDF)

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	feet^1,2

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.

Questions

Well Management Section
651-201-4600 or 800-383-9808
health.wells@state.mn.us

Wells and Borings

Wells Program

Related Topics

Environmental Health Division