Summary of Montana's Water Reuse Guideline or Regulation for Potable Water Reuse
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
- Types of planned potable reuse approved for use in Montana
- Water reuse treatment category/type
- Potable reuse 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, potable water reuse The use of highly treated recycled water for drinking water purposes. This reuse application includes both indirect potable reuse through introduction of recycled water into an environmental buffer such as a surface reservoir or groundwater aquifer, and direct potable reuse through introduction of recycled water into a drinking water system. applications include indirect potable reuse (aquifer or reservoir water augmentation). The source of water treated municipal wastewater Treated 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 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
Potable water in the United States must meet all applicable Safe Drinking Water Act (SDWA) requirements, including its implementing regulations (40 C.F.R. § 141) for chemical and microbial contaminants. Any pollutant discharges from a point source for surface water augmentation must be authorized under a National Pollutant Discharge Elimination Systems (NPDES) permit (40 C.F.R. § 122) or a Montana Pollutant Discharge Elimination Systems (MPDES) permit (Montana DEQ, 2021). Montana indirect potable reuse regulations require specific treatment requirements for certain pathogens and chemicals, which include oxidation, coagulation, filtration and disinfection. The Montana Department of Environmental Quality (DEQ) reviews indirect potable reuse projects on a case-by-case basis. The technical basis for the removal of microbial and chemical contaminants is not explicitly specified.
Types of planned potable reuse approved for use in Montana
Circular DEQ 2 defines the following approved planned potable uses:
- Indirect Potable Reuse
- The conveyance of reclaimed wastewater directly into an aquifer or reservoir used as a raw water source for a drinking water supply with the intent of supplementing the raw water supply.
Water reuse treatment category/type
Class A reclaimed wastewater is required for indirect potable reuse in Montana. The various classes of reclaimed wastewater are defined by their respective treatment requirements and groundwater permit requirements. For Class A water, the minimum treatment requirements are oxidation, coagulation, filtration and disinfection.
Potable reuse specifications
Summary of Montana's Potable 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 (Indirect potable reuse) |
Municipal wastewater |
5-day biochemical oxygen demand (BOD5) |
≤10 mg/L |
Measured following treatment |
|
Total suspended solids (TSS) |
≤10 mg/L |
Measured following treatment |
||
|
Total coliform |
≤2.2 CFU/100 mL (median not to be exceeded in past 7 days) ≤23 CFU/100 mL (single sample maximum) |
Weekly analysis |
||
|
Turbidity |
≤2 NTU (average) ≤5 NTU (not to exceed at any time) |
Continuous monitoring |
||
|
Total nitrogen |
Monitoring only |
Monthly analysis |
Source = Circular DEQ 2
Upcoming state law or policy
No upcoming potable reuse regulations were found for Montana.
References:
Design Standards for Public Sewage Systems, Circular DEQ 2.
EPA-Administered Permit Programs: The National Pollutant Discharge Elimination System, 40 C.F.R. § 122.
Montana Department of Environmental Quality (DEQ). 2021. Permitting and Operator Assistance: Surface Water Discharge Permits (MPDES).
National Primary Drinking Water Regulations, 40 C.F.R. § 141.
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.