Summary of Montana's Water Reuse Guideline or Regulation for Industry
This page is part of the EPA’s REUSExplorer tool, which summarizes the different state level regulations or guidelines for water reuse for a variety of sources and end-uses.
The source water for this summary is Treated Municipal Wastewater.
On this page:
- Technical basis
- Water reuse industrial applications approved for use in Montana
- Water reuse treatment category for industrial applications
- Additional context and definitions
- Water reuse for industrial applications specifications (table)
- Upcoming state law or policy
- References
- Disclaimer
This page is a summary of the state’s water reuse law or policy and is provided for informational purposes only. Please always refer to the state for the most accurate and updated information.
In Montana, water reuse for industryThe use of recycled water for industrial applications, often created at the industrial facility. This includes recycled water generated through onsite processes such as boiler water, cooling water, manufacturing water, and oil and gas production, as well as recycled water generated offsite and imported elsewhere for industrial reuse applications. includes reuse for processes that create aerosols or other mist and processes that do not create aerosols. The source of water treated municipal wastewaterTreated wastewater effluent discharged from a centralized wastewater treatment plant of any size. Other terms referring to this source of water include domestic wastewater, treated wastewater effluent, reclaimed water, and treated sewage. is specified by the state as municipal wastewater. The write-up on this page uses state terms when discussing sources or uses of water that may differ from the Regulations and End-Use Specifications Explorer’s (REUSExplorer’s) terms.
Technical basis
Montana approves the use of recycled water for industrial reuse applications including processes that create aerosols or mists (such as cooling towers, forced air evaporation or spraying) and processes that do not create aerosols (such as heat pumps and boilers) (Circular DEQ 2). Montana requires that reclaimed wastewater reuse projects have documentation from the Department of Natural Resources and Conservation that the change of appropriation or water right was approved, or that no authorization is needed under Title 85, Water Use (Circular DEQ 2). All applicable provisions of the Clean Water Act (CWA) (33 U.S.C. §§ 1251 et seq.), including its implementing regulations, must be met in addition to any state water quality standards. Montana requires that municipal wastewater used for industrial uses be limited to quantities which achieve the desired industrial need, but do not result in a discharge to ground or surface waters unless the industry obtains an appropriate discharge permit for that purpose (Circular DEQ 2). Treatment requirements and performance standards are applied for the removal of pathogen and chemical contaminants for reuse applications related to industrial reuse to ensure “an adequate demonstration of public health and environmental protection” (Circular DEQ 2). The technical basis for developing the specifications and/or removals of microbial contaminants, chemicals and other relevant indicators is not explicitly specified.
Water reuse industrial applications approved for use in Montana
Circular DEQ 2 defines the following approved industrial reuse applications:
- Aerosols or other mist created (e.g., cooling towers, forced air evaporation or spraying) (Class A)
- Aerosols not created (e.g., heat pumps, boilers) (non-discharging recirculation) (Class C)
Water reuse treatment category for industrial applications
The various classes of treatment are defined by their respective treatment requirements and applicable performance standards, differentiated by the degree of additional treatment provided following secondary treatment (Circular DEQ 2). The respective treatment requirements are briefly summarized for industrial reuse applications:
- For Class A reclaimed wastewater, the treatment requirements are secondary treatment, oxidation, coagulation, filtration and disinfection to achieve a BOD and TSS of ≤10 mg/L and a turbidity of ≤2 NTU (average), ≤5 NTU (single sample maximum) and total coliform organisms ≤2.2 CFU/100 mL (7-day median) and ≤23 CFU/100 mL (single sample maximum).
- For Class C reclaimed wastewater, the treatment requirements are secondary treatment, oxidation, settling and disinfection to achieve total coliform organisms ≤23 CFU/100 mL (7-day median) and ≤240 CFU/100 mL (single sample maximum).
Additional context and definitions
In Montana, reclaimed wastewater is defined as “wastewater treated by a public sewage system for reuse for private, public, or commercial purposes” (Circular DEQ 2).
When municipal wastewater is used for industrial uses in areas where workers may be exposed to, or come in direct contact with, reclaimed wastewater, a specific worker safety program must be in place that addresses potential and actual contact with the reclaimed wastewater (Circular DEQ 2). “Although reclaimed wastewater can be deemed safe for workers after a given treatment, there are general precautions for hygiene, emergency situations, and ingestion that must be covered in operation and maintenance manuals or user agreements with the generator. Worker safety programs are viewed as part of proper management of the reclaimed wastewater after meeting permit requirements” (Circular DEQ 2).
Reclaimed wastewater delivered to a commercial building must have adequate backflow prevention on the domestic water line entering the building (Circular DEQ 2). Montana recommends that a cross connection management agreement be in place to protect the water supply in the building from cross connection with reclaimed wastewater. Montana also specifies specific strainers be used at meters and best management practices be implemented when using reclaimed wastewater for industrial uses (Circular DEQ 2).
Montana requires that conveyance systems for the delivery of municipal reclaimed wastewater be easily identifiable; the use of purple piping or purple striped piping is encouraged (MT DEQ 2018). Reclaimed water plumbing must not be cross connected to any potable water supply within the structure. Areas of reclaimed wastewater use must have signs posted at conspicuous public access points that read “Reclaimed wastewater – Do Not Drink” or an approved equivalent warning.
Water reuse for industrial applications specifications
Summary of Montana's Water Reuse for Industrial Applications Reuse Specifications
| Recycled Water Class/Category | Source Water Type | Water Quality Parameter | Specification | Sampling/Monitoring Requirements (Frequency of monitoring; site/ location of sample; quantification methods)* |
|---|---|---|---|---|
|
Class A (Industrial uses where aerosols or other mist are created) |
Municipal wastewater |
Total coliform |
≤2.2 CFU/100 mL (7-day median) |
Weekly analysis |
|
5-day biochemical oxygen demand (BOD5) |
≤10 mg/L |
Measured following treatment |
||
| Total suspended solids (TSS) | ≤10 mg/L | |||
| Turbidity | ≤2 NTU (average) ≤5 NTU (single sample maximum) |
Continuous monitoring | ||
| Total nitrogen | None, monitor only | Monthly analysis | ||
|
Class C (Industrial uses where aerosols are not created) |
Municipal wastewater |
Total coliform |
≤23 CFU/100 mL (7-day median) |
Monthly analysis |
|
Total nitrogen |
None, monitor only |
Source= Circular DEQ 2
* Information about sampling and monitoring requirements such as frequency, site and quantification methods not specifically listed in the table was not explicitly specified in the state-specific regulations.
Upcoming state law or policy
No upcoming regulations related to industrial water reuse were found for Montana.
References:
Clean Water Act, 33 U.S.C. §§ 1251 et seq.
Design Standards for Public Sewage Systems, Circular DEQ 2.
Please contact us at waterreuse@epa.gov if the information on this page needs updating or if this state is updating or planning to update its laws and policies and we have not included that information on the news page.