Holding tanks, mobile tanks and containers are commonly used by commercial, industrial, institutional and municipal facilities - particularly in areas not served by sewers - to store wastewater for off-site disposal, recycling or treatment. Depending on storage vessel functions, wastewater characteristics and facility locations, these tanks and containers may be subject to different federal and state regulations.

All owners and operators of industrial wastewater holding tanks (IWHTs), mobile tanks and containers used exclusively to accumulate or store non-hazardous, non-sanitary wastewater are required to comply with a Massachusetts Department of Environmental Protection (MassDEP) industrial wastewater holding tank regulation (314 CMR 18.00) that took effect in November 2002.

Applicability and requirements

The regulation applies only to facilities that store non-hazardous, non-sanitary wastewater in IWHTs, mobile tanks or containers and intend to truck it directly off-site for disposal, recycling or treatment. The rule establishes specific construction and operation standards, record-keeping requirements and decommissioning procedures for these industrial wastewater storage vessels.

In addition, there is a one-time compliance certification requirement for IWHTs. The certification form (DEP01) replaces holding tank plan approvals (IW-29 and WP-56) that were required before November 2002. IWHTs previously approved by DEP, as well as mobile tanks and containers, are exempt from the certification requirement.

Regardless of installation date or certification status, owners and operators of storage vessels subject to the regulation are required to comply with all applicable procedures, requirements and standards.


The regulation does not apply to tanks and containers that are used for:

  • Sanitary wastewater storage regulated under 310 CMR 15.00 (Title 5)
  • Production processes and wastewater treatment systems
  • Non-contact cooling water or heating or cooling condensate storage
  • Waste site cleanup projects regulated under 310 CMR 40.0000
  • Hazardous waste storage regulated under 310 CMR 30.000
  • Facilities regulated under the MassDEP Environmental Results Program (dry cleaners, photo processors and printers)

For additional information

You may download a copy of the DEP01 Industrial Wastewater Holding Tank certification package from the MassDEP Website: Environmental Results Program & Compliance Certification Forms