The following list is for informational purposes only and does not mean the well types are allowed in Washington.

Class V wells are allowed in Washington if they can meet the requirements of Chapter 173-218 WAC (Underground Injection Control Program) and Chapter 173-200 WAC (Water Quality Standards for Ground Waters of the State of Washington).

Visit for additional information on the different Class V wells used in the United States.



(Previous EPA well code)

Well Types

5H1 (5D2) Storm Water Drainage Wells – receive storm water runoff from paved areas, including parking lots, streets, residential subdivisions, building roofs, highways, etc.
5H (5D4) Industrial Stormwater Drainage Wells – include wells located in industrial areas which primarily receive storm water runoff but are susceptible to spills, leaks, or other chemical discharges.
5H2 (5F1) Agricultural Drainage Wells – receive irrigation tailwaters, other field drainage, animal yard, feedlot, or dairy runoff, etc.
5H3 (5G30) Drainage Wells – are used for disposing water from sources other than direct precipitation. Examples of this well type include: landslide control drainage wells, potable water tank overflow drainage wells, swimming pool drainage wells, and lake level control drainage wells.
5C2 (5A7) Heat Pump/Air Conditioning Return Flow Wells – re-inject ground water used to heat or cool a building in a heat pump system – shallow wells.
5A18 Cooling water with no additives.
5A19 Cooling water with additives.
5E (5W10) Cesspools – include multiple dwelling, community or regional cesspools, or other devices that receive wastes and which must have an open bottom and sometimes have perforated sides. Must serve greater than 20 persons per day if receiving solely sanitary wastes. (Settling of solids)
5F (5W11,5W32, 5W31) Septic Systems (Undifferentiated, drainfield and well disposal) – are used to inject the waste or effluent from a multiple dwelling, business establishment, community, or regional business establishment septic tank. Must serve greater than 20 persons per day if receiving solely sanitary wastes. (Primary Treatment)
5A (5W20) Industrial Process Water and Waste Disposal Wells – are used to dispose of a wide variety of wastes and wastewaters from industrial, commercial, or utility processes. Industries include refineries, chemical plants, smelters, pharmaceutical plants, laundromats and dry cleaners, tanneries, laboratories, petroleum storage facilities, electric power generation plants, car washes, electroplating industries, etc.
5K (5X28) Automobile Service Station Disposal Wells – inject wastes from repair bay drains at service stations, garages, car dealerships, etc.
5B2 (5B22) Saline Water Intrusion Barrier Wells – are used to inject water into fresh water aquifers to prevent intrusion of salt water into fresh water aquifers.
5B3 (5S23) Subsidence Control Wells – are used to inject fluids into a non-oil or gas producing zone to reduce or eliminate subsidence associated with overdraft of fresh water and not used for the purpose of oil natural gas production.
5B4 (5R21) Aquifer Storage and Recover Wells – are used to recharge depleted aquifers and may inject fluids from a variety of sources such as lakes, streams, domestic wastewater treatment plants, other aquifers, etc.
5B6 (5X26) Aquifer Remediation Related Wells – include wells used to clean up, treat, or prevent contamination of ground water. These wells may be associated with RCRA, Superfund or MTCA projects.
5G2 Experimental CO2 Sequestration wells.
5X (5X27) Other Wells – include any other unspecified Class V wells.


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Last updated March 2016