&EPA
United States
Environmental Protection
Agency
Office of Water
4603
EPA811-F-94-003
June 1994
EPA Efforts to Reduce Risks from Microbial Contaminants
and Disinfectants/Disinfection By-products
Balancing Risks
• Public water systems use disinfection to kill
harmful microbial contaminants that can cause
illness, and may even be fatal for those with
weak immune systems. However, disinfection
and the resulting by-products also pose risks,
including potential increases in cancer rates and
liver and kidney damage. The challenge is to
strike an appropriate balance between these
two risks so that public health is adequately
protected.
Regulatory Negotiation
• To help meet this challenge, EPA convened a
negotiating team in November 1992 to assess
the risks and determine the most appropriate
course of action. The negotiating team
included representatives from:
- Public water systems
- State and local health agencies
- Environmental organizations
- Consumer groups
- Federal, state, and local governments
• The negotiators agreed to a three-part pro-
gram:
1. Modest interim controls of disinfectants
and disinfection by-products (D/DBP). and
microbial contaminants
Based on existing data, interim controls were
determined for controlling D/DBPs and microbial
contaminants. These controls are being pro-
posed by EPA as a D/DBP rule and an en-
hanced surface water treatment (ESWT) rule for
microbial control.
Under the proposed D/DBP rule, communities
would be required to meet new standards for
disinfectants and disinfection by-products. The
existing standard for trihalomethanes would be
lowered and extended to cover all systems,
regardless of size. The rule would also establish
six new maximum contaminant levels to control
excessive use of disinfectants and reduce by-
product formation.
The ESTW rule proposes a number of treatment
options for protecting water systems against
harmful protozoa, such as Giardia and
Cryptosporidium. and viruses. It would require
systems with poorer source water to provide
greater control than is currently required under
the existing surface water treatment regulation. A
sanitary survey would be required every five
years so that public water systems would peri-
odically evaluate the effectiveness of their
operations. The proposed rule would apply to
those systems serving 10,000 people or more;
however, the sanitary survey would also be
applicable to those systems serving less than
10,000 people.
-------
&EPA
United States
Environmental Protection
Agency
Office of Water
4603
EPA811-F-94-003
June 1994
EPA Efforts to Reduce Risks from Microbial Contaminants
and Disinfectants/Disinfection By-products
Balancing Risks
• Public water systems use disinfection to kill
harmful microbial contaminants that can cause
illness, and may even be fatal for those with
weak immune systems. However, disinfection
and the resulting by-products also pose risks,
including potential increases in cancer rates and
liver and kidney damage. The challenge is to
strike an appropriate balance between these
two risks so that public health is adequately
protected.
Regulatory Negotiation
• To help meet this challenge, EPA convened a
negotiating team in November 1992 to assess
the risks and determine the most appropriate
course of action. The negotiating team
included representatives from:
- Public water systems
- State and local health agencies
- Environmental organizations
- Consumer groups
- Federal, state, and local governments
• The negotiators agreed to a three-part pro-
gram:
1. Modest interim controls of disinfectants
and disinfection by-products (D/DBP). and
microbial contaminants
Based on existing data, interim controls were
determined for controlling D/DBPs and microbial
contaminants. These controls are being pro-
posed by EPA as a D/DBP rule and an en-
hanced surface water treatment (ESWT) rule for
microbial control.
Under the proposed D/DBP rule, communities
would be required to meet new standards for
disinfectants and disinfection by-products. The
existing standard for trihalomethanes would be
lowered and extended to cover all systems,
regardless of size. The rule would also establish
six new maximum contaminant levels to control
excessive use of disinfectants and reduce by-
product formation.
The ESTW rule proposes a number of treatment
options for protecting water systems against
harmful protozoa, such as Giardia and
Cryptosporidium. and viruses. It would require
systems with poorer source water to provide
greater control than is currently required under
the existing surface water treatment regulation. A
sanitary survey would be required every five
years so that public water systems would peri-
odically evaluate the effectiveness of their
operations. The proposed rule would apply to
those systems serving 10,000 people or more;
however, the sanitary survey would also be
applicable to those systems serving less than
10,000 people.
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