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 Remove suspended material (turbidity) and color Eliminate pathogenic organisms Treatment technologies largely based on coagulation and flocculation

Surface Water Treatment Sedimentation basin Screen Surface water from supply Rapid Mix Flocculation Basin Rapid Sand Filter Sludge Disinfection To Distribution System Storage

Groundwater Treatment Primary objectives are to Remove hardness and other minerals Eliminate pathogenic organisms Treatment technologies largely based on precipitation

Groundwater Treatment from wells Sedimentation basin Sludge Recarbo-nation To Distri- bution System Rapid Mix Flocculation Basin Disinfection Storage CO2