ENSC_103 Lecture 11: Drinking Water

Fast facts about public water systems in the US

- 155,693 public water systems in the United States

- 52,110 (33.5%) are community water systems (CWS)

- 103,583 (66.5%) are non-community water systems (majority)

- 84,744 transient systems and 18,839 nontransient systems̈

- >286 million Americans rely on tap water from CWSs

- Small proportion (8%) of community water systems provide water to majority (82%) of the US population through large municipal water systems̈

- Majority of community water systems (78%) are supplied by groundwater, but more people (68%) rely on community water systems that use surface water

Safe Drinking Water Act (SDWA) of 1974:

- Overall purpose

Provides the US EPA authority to protect public health by regulating the nation's public drinking water supply

*sources are also regulated - anything feeding into these reservoirs)

Safe Drinking Water Act (SDWA) of 1974:

- Drinking water standards

- Primary standards: protect human health from microbial and chemical contaminants

- Secondary standards: ensure that drinking water is aesthetically pleasing with respect to temperature, color, taste, and odor

Waterborne disease outbreaks associated with drinking water (N = 851), by year and etiology - United States, 1971-2010

*etiology- bacteria, chemical, etc.

*decline overtime driven by implementation of legislation in mid 70s & also unidentified categories

*later cases include majority of legionella

Legionnaires' disease

- Source

- Injestion of water contaminated with the bacterium Legionella

- Grow best in warm water

- Mist or vapor from improperly treated hot tubs a common source

*usually in plumbing & end up aerosolizing

Legionnaires' disease

- Symptoms

- Similar to many other forms of pneumonia

- Cough; shortness of breath; high fever; muscle aches; headaches

Legionnaires' disease

- possible complications

- Lung failure

- Death (5-30%)

Etiology of drinking water outbreaks and outbreak- related cases in the US (2009-2010) vs. Predominant illnesses in drinking water outbreaks and outbreak- related cases in the US (2009-2010)

Etiology

* more smaller outbreaks associated with legionella

*total cases (across all 33 outbreaks-cluster of cases) are mostly non-legionella

Predominant illnesses

- outbreaks: ARI- dominant, legionella

- cases: AGI- dominant, nonlegionella

Quality of water from public-supply wells in the US, 1993-2007

- Sampled source (untreated-raw water) groundwater from 932 public-supply wells(to see contaminant load)

- Public wells located in selected parts of 41 states; covers 30 regionally extensive water-supply aquifers

- Assessed 337 naturally occurring and man-made contaminants

- 279 contaminants analyzed not regulated in drinking water by EPA

Disinfection byproducts

formed when disinfectants used in a water treatment react with bromide and/or natural organic matter (i.e., decaying vegetation) present in the source water; health effects within human populations are uncertain due to use of high-dose toxicological studies

John Snow revisited: London cholera epidemic of 1854

*Cluster of Cholera related deaths

*not contaminated was treated w/ Cl and more upstream

- from this association John Snow identified the source of water based on Cl levels

Vibrio cholerae

- discovered within India by Robert Koch (1843-1910 German physician and founder of modern bacteriology) in 1884

Germ theory: cholera caused by a germ cell, not yet identified.

*induced via a bug

Typhoid fever in the United States

- Chlorination was introduced in 1908 to treat drinking water supplies, and chlorine is still the most common disinfectant used in the US.

*driven by consumption of contaminated drinking water

Typhoid fever

- Source

Injestion of water contaminated with the bacterium Salmonella enterica typhi

Typhoid fever

- Symptoms

- Sustained fever up to 103°-104°F

- Stomach pains, headache, or loss of appetite

- Rash of flat, rose-colored spots

Typhoid fever

- Annual Cases

- United States - 5,700 cases per year; up to 75% acquired while traveling overseas

- Developing world - 21.5 million cases and 200,000 deaths per year

*cases not acquired domestically

Global distribution of typhoid fever

*to prevent this all that is needed is the introduction of chlorination

* get vaccinated before traveling to these areas

Distribution of Earth's Water

*There is a very limited supply of freshwater

only 2.5% of total global water is freshwater and 30.1% of that is groundwater and 1.3% surface water and other freshwater

Principal aquifers in the US

*if any of these aquifers are contaminated- game over

- want to prevent vertical movement of contaminants that have low Kd

- only way to clean is to pump out, treat, and pump back in (expensive and not sustainable)

Rivers and lakes in the US

*more infusion of freshwater on the East Coast- no issue of water availability& no need of aquifers from other cities

- urbanizes S. California is heavily dependent on water from other states (CO River-surface water)

- b/c heavily contaminated groundwater - most Superfund sites are groundwater specific

Community water systems

- Supplies water to the same population year-round

- Serves at least 25 people at their primary residences or at least 15 residences that are primary residences

-low threshold

Non-community water systems

- Transient water systems: Provide water to 25 or more people for >60 days/year, but not to the same people and not on a regular basis

- Non-transient water systems: Regularly supply water to at least 25 of the same people between 6- 12 months/year

*risk- EPA will not hold private wells to be regulated

Safe Drinking Water Act (SDWA) of 1974:

- Amendments

- Expanded and strengthened in 1986 and 1996

- Require that drinking water and its sources, such as rivers, lakes, reservoirs, springs, and groundwater wells serving more than 25 individuals be protected

Waterborne disease outbreaks associated with drinking water (N = 33) - 2009-2010

*based on a cluster of cases (could even be only 5)

- looking at a year

Water systems associated with drinking water outbreaks and outbreak- related cases in the US (2009-2010) vs. Deficiencies assigned to drinking water outbreaks and outbreak- related cases in the US (2009-2010)

Water systems

- outbreaks: most water is from community water system (in hot tubs)

- cases: most water is from community water systems (in homes)

Deficiencies assigned- outbreaks: majority- legionella in premise plumbing system- cases: most non-legionella, GI cases were from distribution systems

Public-supply well locations and data summary

*Since 2014, usually only measured one time

- each dot = case

- lots of clusters of cases

Unconfined vs. confined aquifers

*most cases at unconfined

- contaminants less likely to break through the low permeability confining layer

- unconfined: shallow well

-confined: deep well

Chlorination produces unwanted disinfectant byproducts

Dysinfection Byproducts: Total trihalomethanes (*trihalomethanes- methane, where hydrogen has been replaced w/ 3 halogens (ex: Cl)), bromate, chlorites, Haloacetic acids