Drinking Water Quality and Health

Engineered Water Systems

Water and Health

• 80% of sickness in the world is caused by inadequate water supply or sanitation

• 40% of the world population does not have access to safe drinking water

• It is estimated that water-borne diseases kill 25,000 people per day

• In many populated areas of the world, water-borne diseases represent the leading cause of death

Drinking Water Regulation in the U.S.

• 1912 – First regulated in U.S. with Public Health Service Act– relied on voluntary and local efforts– dramatic decrease in water-borne

disease over the next 30 years• 1974 – Federal oversight of all public water

supplies with Safe Drinking Water Act (SDWA)

• 1986 – Current framework established with SWDA Amendments

Sizes of Particles in Water

Palatable vs. Potable

• Palatable– aesthetically pleasing– considers the presence of chemicals

that do not pose a threat to human health

– palatability affected by chloride, color, corrosivity, iron, manganese, taste and odor, total dissolved solids, turbidity

Potable Water

• Potable– safe to drink– not necessarily aesthetically pleasing– potability affected by

•microbials (e.g. Giardia, Cryptosporidium)

•organic chemicals (e.g., alachor, chlordane, 1,2-dichloroethylene, disinfection by-products)

• inorganic chemicals (e.g., cadmium, copper, lead, mercury)

•Radio-nuclides

Palatable and Potable

• The goal of municipal water treatment is to provide water that is both palatable and potable

• Palatability and Potability regulated under Safe Drinking Water Act– Palatability: Secondary Maximum

Contaminant Levels (SMCLs)– Potability: Primary Maximum Contaminant

Levels (MCLs) - (for systems serving more than 25 persons per day for greater than 60 days per year)

Primary MCLs (mg/L)

Primary MCLs (mg/L)

Primary MCLs (mg/L)

Primary MCLs (mg/L)

Secondary MCLs (mg/L)

Sources of Drinking Water• Groundwater

– shallow wells– deep wells

• Surface water– rivers– lakes– reservoirs

Ground- vs. Surface Water

Groundwater• constant composition• high mineral content• low turbidity• low color• low or no D.O.• high hardness• high Fe, Mn

Surface water• variable composition• low mineral content• high turbidity• colored• D.O. present• low hardness• taste and odor

Surface Water Treatment

• Primary objectives are to

1. Remove suspended material (turbidity) and color

2. Eliminate pathogenic organisms

• Treatment technologies largely based on coagulation and flocculation

Surface Water Treatment

Surface water from supply

Rapid Mix

FlocculationBasin

Sedimentation

basin

SludgeRapid Sand Filter Disinfection

StorageTo DistributionSystem

Screen

Groundwater Treatment

• Primary objectives are to

1.Remove hardness and other minerals

2.Eliminate pathogenic organisms• Treatment technologies largely based on

precipitation

Groundwater Treatment

Ground waterfrom wells

Sedimentation

basin

SludgeRecarbo-nation

To Distri-butionSystem

Rapid Mix

FlocculationBasin

Disinfection

Storage

CO2