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Please note: This summary is provided to help you understand the regulations. Consult the references provided for links to the full text of the regulations.

Cleaning, Tank Interiors

Road Rail Air Water

The wastewater generated when tanks are cleaned contains residues of whatever was in the tank. Since many of these materials can have harmful effects when released into the environment, the disposal of tank cleaning wastewater is governed by federal rules. Different rules apply to trucks, railcars, and interior barges on the one hand, and maritime vessels on the other.

Regulations impacting interior tank cleaning have been promulgated by U.S. EPA and the U.S. Coast Guard.

Other types of cleaning operations are covered elsewhere on TERC, including:

Who is covered by the regulations?

Most tank interior cleaning operations are covered by EPA effluent guidelines, including truck, rail, and barges or ships when discharging to a publicly owned treatment works (POTW) or waters of the U.S. (e.g., lakes, steams, rivers, intercoastal waters and territorial seas). U.S. Coast Guard regulations apply to all U.S. flagged ships anywhere in the world and to all foreign flagged vessels operating in the navigable waters of the U.S., or while at a port under U.S. jurisdiction.

The wastewater flows covered by regulations include all contact washwaters which have come into direct contact with a tank or container interior. This includes pre-rinse cleaning solutions, chemical cleaning solutions, and final rinse solutions.

What is the purpose of the regulations?

The primary pollutant output of tank cleaning operations is wastewater contaminated with tank residues (e.g., petroleum products, coal, organic chemicals, inorganic chemicals, compressed gases, fertilizers, pesticides, food products, paints, inks, glues, soaps) and cleaning solutions. These pollutants degrade water bodies and have adverse effects on marine life.


Interior tank cleaning can be performed either at carrier or shipper-owned facilities or at a tank cleaning service facility (commonly called Transportation Equipment Cleaning Industry or TECI). The process used can differ significantly depending on the residues to be cleaned and the extent to which a tank needs to be cleaned prior to reuse. Most truck, barge and ship tanks are in dedicated service (i.e., carries one commodity only), however, a significant number are non-dedicated and must be cleaned after every trip to prevent contamination of materials from one cargo to the next.

The following tank cleaning procedures are typically carried out at tank cleaning facilities:

  • Shipping papers are checked to identify the cargo last carried
  • Next cargo is determined, if possible
  • Residual cargo "heel" is removed and segregated for off-site disposal
  • Tank is rinsed
  • Tank is washed
  • Tank is rinsed
  • Tank is dried

Washing is performed either manually with hand held sprayers, or automatically with high pressure spinner nozzles or "butterworths." The volumes of water used, the types of wastes generated, and the cleaning time can vary widely.

Option 1 - Discharge to a POTW
Discharging to a Publically Owned Treatment Works (or POTW) is referred to as an "indirect discharge," because your wastewater is going to a POTW before it is subsequently discharged to a stream or other water body. This is viable when the facility is located in an area served by a municipal sanitary sewer system.

Before you initiate option 1, you must acquire a permit or written notification from either your local sewer district or state environmental agency. You will also have to meet certain rules found in federal and state regulations, including:

  • You are prohibited from discharging any pollutant, including oil, that may upset or interfere with the sewage treatment processes or pass through the system untreated.
  • You cannot discharge pollutants (e.g., solvents) that may cause a fire in the sewer system.
  • You cannot discharge pollutants such as sludge (e.g., grease, dirt) that may clog the sewer system.
  • You must meet discharge standards for indirect discharges found in 40 CFR 442.
  • You must comply with notification, monitoring, reporting and record keeping requirements found in 40 CFR 403.12.

To meet sewer discharge standards, you may need to install equipment such as an oil/water separator to prevent oil and sludge from being discharged to the sewer. This is referred to as "pretreatment." The oil and sludge collected by pretreatment equipment will have to be periodically removed and disposed of, possibly as a hazardous waste (you must make a hazardous waste determination). Other types of treatment that are commonly employed with wastewater include pH adjustment, settling, and metals precipitation processes. For more information see Pretreatment Standards and Limits.

Option 2 - Discharge to a Stream
Discharging to a stream or other water source ("direct discharge") is a potential option, but one that requires a National Pollutant Discharge Elimination System (NPDES) permit or state equivalent. If you obtain this type of permit, you will be required to meet the discharge standards found in 40 CFR 442 and demonstrate that you are in compliance by frequently collecting samples of your wastewater and having them analyzed at a laboratory. You will also have significant reporting and recordkeeping responsibilities.

Maritime rules (administered by the U.S. Coast Guard). The International Convention for the Prevention of Pollution from Ships ("MARPOL" short for marine pollution) is the international treaty regulating disposal of wastes generated by normal operation of vessels. MARPOL 73/78 is implemented in the U.S. by the Act to Prevent Pollution from Ships, under the lead of the U.S. Coast Guard.

Cargo hold interiors are predominantly cleaned at sea by the tanker crew, with wastewater either discharged shore side at ballast water treatment facilities or at sea within the provisions of the MARPOL. A relatively small percentage of cargo hold interiors are cleaned shore side to facilitate inspection and repair and are performed concurrently with ballast tank and bunker (fuel) tank cleanings.

The applicable MARPOL rules depend on they type of cargo:

Use the contact information under More Resources (below) with questions regarding U.S. Coast Guard regulations relating to tank cleaning.

More Resources

Transportation Equipment Cleaning Effluent Guidelines Fact Sheet. Overview of the rule, including applicability.

Transportation Equipment Cleaning Effluent Guideline Development Document (EPA-821-R-00-012; June 2000). Background information on promulgated rule.

EPA Transportation Equipment Cleaning Effluent Guidelines point of contact:

U.S. Coast Guard Contact MARPOL Rules information:

Environmental Standards Division (CG-5224)
U.S. Coast Guard Headquarters
2100 Second Street SW
Washington, DC 20593
Tel: 202-372-1402