Drinking Water Quality

Question 0

Safe Drinking Water Act (SDWA)

Answer 0

• Authorizes EPA to set national health based standards for drinking water
• naturally occurring & man made contaminants
• primary standards

Question 1

2 systems work to stop the spread of waterborne diseases

Answer 1

1) water collection, treatment, and distribution to provide safe drinking water
* regulation: Safe Drinking Water Act (SDWA)

2) waste water collection and treatment to remove contaminants e.g. BOD, nutrients, pathogens, before release to the environment
* regulation: Clean Water Act

Question 2

Drinking water standards fall into 2 categories…

Answer 2

1) National Primary Drinking Water Regulation (primary standards)
2) National Secondary Drinking Water Regulation (secondary standards)

Question 3

Primary standards

Answer 3

• legally enforceable standards

* involves MCLs, MCLGs, TT, MRDLs, MRDLGs

Question 4

Secondary standards

Answer 4

• EPA recommends
• non-enforceable
• considered guidelines

Question 5

Maximum Contaminant Level (MCL)

Answer 5

• EPA balances public health benefit against economic and technical considerations
• EPA sets goals (MCLGs)

Question 6

MCLGs

Answer 6

• cant be enforced
• represent no known health effects (e.g. MCLGs for carcinogens are set to zero)
• don’t consider technological feasibility or cost

Question 7

MCLs a reviewed periodically to determine…

Answer 7

If they can be brought closer to the MCLGs

Question 8

For some contaminants, a Treatment Technique (TT) is required rather than an MCL…

Answer 8

• Because contaminant may be too difficult or costly to detect
• e.g. Viruses, Giardia, cryptosporidium require water filtration as TT

Question 9

Primary standards are classified into categories (6)

Answer 9

1) microbiological contaminants
2) disinfectants
3) disinfectant-by-product
4) Inorganics
5) organics
6) Radionuclides

Question 10

Microbiological Contaminants –Total Coliforms

Answer 10

• known as “indicator organisms”
• enteric organisms (live in intestine of human/ other species)
• presence indicates feels contamination

Question 11

Disinfectants

Answer 11

• used to destroy pathogens

* primary standards involve Maximum Residual Disinfectant Level (MRDL) and MRDLGs

Question 12

Disinfectant-by-product

Answer 12

React with naturally occurring organic & inorganic matter in water to form DBP

Question 13

Standards for DBP involve MCLs and MCLGs for…

Answer 13

1) HAA5

2) TTHMs