Surface Water Treatment Rules

Rule Summary

This site provides information about the suite of the Surface Water Treatment Rules (SWTRs).

The purpose of the Surface Water Treatment Rules (SWTRs) is to reduce illnesses caused by pathogens in drinking water. The disease-causing pathogens include Legionella, Giardia lamblia, and Cryptosporidium.

The SWTRs requires water systems to filter and disinfect surface water sources. Some water systems are allowed to use disinfection only for surface water sources that meet criteria for water quality and watershed protection.

The following is a brief overview of the major components of each rule. This combination of rules is designed to provide protection from microbial pathogens. Simultaneously, the rules minimize health risks to the population from disinfection byproducts.

Surface Water Treatment Rule (SWTR) – June 1989:

Applies to all public water systems (PWSs) using surface water sources or ground water sources under the direct influence of surface water (GWUDI)
Requires most water systems to filter and disinfect water from surface water sources or GWUDI
Establishes maximum contaminant level goals (MCLGs) for viruses, bacteria and Giardia lamblia
Includes treatment technique (TT) requirements for filtered and unfiltered systems to protect against adverse health effects of exposure to pathogens

Interim Enhanced Surface Water Treatment Rule (IESWTR) – December 1998:

Applies to all public water systems using surface water, or GWUDI, that serve 10,000 or more persons
Sets a maximum contaminant level goal (MCLG) of zero for Cryptosporidium
Sets a 2-log Cryptosporidium removal requirements for systems that provide filtration
Requires that watershed protection programs address Cryptosporidium for system that are not required to provide filtration
Requires certain public water systems to meet strengthened filtration requirements
Establishes requirements for covers on new finished water reservoirs
Requires sanitary surveys, conducted by states, for all surface water systems regardless of size
Requires systems to calculate levels of microbial inactivation to address risk trade-offs with disinfection byproducts

Filter Backwash Recycling Rule (FBRR) – June 2001:

Applies to all public water systems using conventional or direct filtration to treat surface water, or GWUDI, regardless of size
Requires public water systems (PWSs) to review their backwash water recycling practices to ensure that they do not compromise microbial control
Requires recycled filter backwash water to go through all processes of a system’s conventional or direct filtration treatment.

Long Term 1 Enhanced Surface Water Treatment Rule (LT1ESWTR) – January 2002:

Applies to all public water systems using surface water, or GWUDI, serving fewer than 10,000 persons
Sets a maximum contaminant level goal (MCLG) of zero for Cryptosporidium
Sets a 2-log Cryptosporidium removal requirements for systems that filter
Requires that watershed protection programs address Cryptosporidium for system that are not required to provide filtration
Requires certain public water systems to meet strengthened filtration requirements
Requires systems to calculate levels of microbial inactivation to address risk trade-offs with disinfection byproducts

Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) – January 2006:

Applies to all PWSs that use surface water or GWUDI
Targets additional Cryptosporidium treatment requirements to higher risk systems
Requires provisions to reduce risks from uncovered finished water storage facilities
Provides provisions to ensure that systems maintain microbial protection as they take steps to reduce the formation of disinfection byproducts

SWTRs Quick Reference Guides

Comprehensive Surface Water Treatment Rules Quick Reference Guide: Systems Using Conventional or Direct Filtration (PDF)(4 pp, 254 K, About PDF) EPA 816-F-04-003)
Comprehensive Surface Water Treatment Rules Quick Reference Guide: Systems Using Slow Sand, Diatomaceous Earth, or Alternative Filtration (PDF)(4 pp, 130 K, About PDF) EPA 816-F-04-002
Comprehensive Surface Water Treatment Rules Quick Reference Guide: Unfiltered Systems (PDF)(4 pp, 248 K, About PDF) EPA 816-F-04-001
Interim Enhanced Surface Water Rule: A Quick Reference Guide (PDF)(2 pp, 65 K, About PDF) EPA 816-F-01-001
Long Term 1 Enhanced Surface Water Treatment Rule: A Quick Reference Guide (PDF)(2 pp, 298 K, About PDF) EPA 816-F-02-001
Long Term 2 Enhanced Surface Water Treatment Rule: A Quick Reference Guide For Schedule 1 Systems (PDF)(2 pp, 173 K, About PDF) EPA 816-F-06-005
Long Term 2 Enhanced Surface Water Treatment Rule: A Quick Reference Guide For Schedule 2 Systems (PDF)(2 pp, 173 K, About PDF) EPA 816-F-06-006
Long Term 2 Enhanced Surface Water Treatment Rule: A Quick Reference Guide For Schedule 3 Systems (PDF)(2 pp, 173 K, About PDF) EPA 816-F-06-007
Long Term 2 Enhanced Surface Water Treatment Rule: A Quick Reference Guide For Schedule 4 Systems (PDF)(2 pp, 173 K, About PDF) EPA 816-F-06-008

Rule History

EPA has developed the Surface Water Treatment Rules (SWTRs) to improve your drinking water quality. The regulations provide protection from disease-causing pathogens, such as Giardia lamblia, Legionella, and Cryptosporidium. The regulations also protect against contaminants that can form during drinking water treatment.

Pathogens, such as Giardia, Cryptosporidium and Legionella, are often found in water. If consumed, these pathogens can cause gastrointestinal illness (e.g., diarrhea, vomiting, cramps) and other health risks. These illnesses may be severe and sometimes fatal for people with weakened immune systems. Cryptosporidium is a significant concern in drinking water because it is resistant to chlorine and other disinfectants.

The Surface Water Treatment Rules were established to protect against these pathogens. To protect public health, drinking water from lakes, rivers streams and some other sources needs to be treated. This treatment includes disinfection and, in most cases, filtration.

Federal Register Notices:

Filtration, Disinfection; Turbidity, Giardia lamblia, Viruses, Legionella, and Heterotrophic Bacteria; Final Rule (June 29, 1989)(300 pp, 74 MB, About PDF)
Interim Enhanced Surface Water Treatment Rule; Final Rule (December 16, 1998)(44 pp, 500 K, About PDF)
Final Revisions to the Interim Enhanced Surface Water Treatment Rule (IESWTR), the Stage 1 Disinfectants and Disinfection Byproducts Rule (Stage 1DBPR), and Revisions to State Primacy Requirements to Implement the Safe Drinking Water Act (SDWA) Amendments Final Rule (January 16, 2001)(11 pp, 278 K, About PDF)
Final Filter Backwash Recycling Rule (June 8, 2001)(20 pp, 241 K, About PDF)
Final Long Term 1 Enhanced Surface Water Treatment Rule (June 14, 2002)(33 pp, 300 K, About PDF)
Final Long Term 2 Enhanced Surface Water Treatment Rule (January 5, 2006)(133 pp, 4.4 MB, About PDF)
- Correction to Long Term 2 Enhanced Surface Water Treatment Rule (January 30, 2006)(1 p, 120 K, About PDF)
- Correction to Long Term 2 Enhanced Surface Water Treatment Rule (February 6, 2006)(1 p, 120 K, About PDF)

Compliance

EPA provides guidance documents to help states and public water systems implement the Surface Water Treatment Rules (SWTRs).

Information about Disinfectant Byproducts