Water Supply & Management Obj: Discuss the nature, importance and sources of water.

Water Composition  Water is made from hydrogen and oxygen  Water chemistry: The study of the composition of water  Water found in nature is not pure  Water can be made pure by distillation  Boiling water  Collecting its steam vapor  Allowing it to cool

Physical State of Water  Solid: Ice forms when water freezes at 32 degrees F  Liquid: Water  Gas or water vapor: steam; forms when water boils

Water Salinity  Saline water: Water that contains salt  Water is classified into 3 categories based on salt content  Freshwater  Little or no salt  Salt < 3ppt (parts per thousand)  3% of earth’s water  Brackish Water  Mix of fresh water and salt water  Estuaries  Salt Water  Salt content > 16.5ppt  97% of earth’s water  Desalination: process of removing salt from water

Importance of Water  Water supports life processes  Needed for functions of life  Human body=65%  Too dry? Use irrigation!  Water for daily living  People in North America use more water than other countries  Average person in USA uses 100 gallons of water each day!  Climate is influenced by water since water moderates the earth’s temperature  Water is used in manufacturing  Processing food, refining oil, making steel, producing paper  Water is used in recreation  Swimming, boating, fishing, skiing, rafting, canoeing, hunting water animals  Water is used in transportation

Sources of Water Surface Water  Water from lakes, streams, reservoirs, and oceans  Water found on earth’s surface  Watershed: an area of land from which all of the water that does not infiltrate the soil runs to a downhill location Ground Water  Water from within the earth  Found in aquifers; may be porous, sand, gravel, or limestone that hold water  Must be managed & conserved  The Ogallala aquifer provides 1/3 of all groundwater used in irrigation in the US  Makes up the vast majority of the freshwater supply  Springs & streams  Water pumped to the surface

Water Storage, Distribution & Management

Water Storage  Water must be stored so it is not polluted or lost for storage  2 types of storage  Natural water storage: storage in lake, sea, ocean or aquifer  Artificial water storage: storage in a tank, reservoir or other structure

Water Distribution  Moving water from its source to where it is needed  Aqueducts are channels for carrying water  Pipe systems are also used  Many storage tanks are elevated to provide pressure to help in distribution

Water Management  Providing potable water  Potable water: water that is safe for humans to use for drinking, cooking and washing

Characteristics of Potable Water  Odor & Taste  Varies depending on source  Some systems add chlorine to control water quality; kills bacteria & oxidizes iron  Color  People prefer clear  Not all unclear water is bad  pH  Neutral water: pH ranges from  Treatments are used to adjust water pH to  Chemical & Pesticide Residues  Coliform Bacteria  Water contaminated with human waste  E. Coli  Alkalinity  The presence of salts of weak acids in the water  Related to hardness  Hardness: concentration of calcium & magnesium ions in water  Dissolved Solid Materials & Turbidity  Water may have dissolved materials in it  Turbidity is the result of suspended solid material; can appear cloudy  Heavy Metals  Mercury & Lead can pose health problems if present in water

Water Treatment  Water may need treatment  POU (Point of Use filtration)-water is treated in home or business  Some can be used as is  Well Water  Often needs no treatment  May need chlorination sometimes  Some homes use softeners  Subsurface Water  Generally needs treatment 1. Screening-remove large objects 2. Presedimentation (river water) & sedimentation (surface water) 3. Chlorination-chlorine added to kill bacteria 4. Final filtration-water is filtered through sand & charcoal filters

So, what’s in a bottle of water?