Desalination Also called desalinization Removes salts from water Two processes can be used Distillation boils water out Reverse osmosis filters water out

Water Use Humans use water for many functions Drinking Household and personal cleanliness Industry Agriculture Largest use of water worldwide Not all nations have equal access to water National rates of water consumption vary widely

Agriculture – Furrow Irrigation Oldest method of irrigation Easy and inexpensive Dig trenches in between rows of crops then fill trenches with water 35% of the water is lost to runoff or evaporation

Agriculture – Flood Irrigation Covers an entire field with water and allows water to soak in Can inhibit plant growth 20-30% of the water is lost to runoff or evaporation

Agriculture – Spray Irrigation Sprays water over crops Requires more equipment than flood or furrow irrigation 5-25% of the water is lost to evaporation or runoff

Agriculture – Drip Irrigation Uses a drip hose to deliver water to a specific area Hoses can be buried, which only lose 5% of the water to evaporation or runoff and prevents weeds Best for perennial crops so hoses don’t have to be moved every year

Hydroponic Agriculture Is growing crops in greenhouses with no soil and little pesticide Uses a nutrient-rich water solution Uses 95% less water than the most efficient irrigation techniques Can produce more crops per hectare Can be used all year

Industry Hydroelectric power Thermoelectric power Paper Metal refining Uses 50% of all industrial water Returns it to its source Thermoelectric power Used for cooling Generates steam Paper Uses 125 L (33 gal) of water to make 1 kg Metal refining

Water Ownership Is not easy to define Water sources cross state and national boundaries Different groups require different types of access One proposed solution is to make water a free-market commodity Read p. 256-259!

Water Conservation Reduce use, recycle Dual-flush toilets 6 L flush for solid waste 3 L flush for liquid waste Gray water recycling Reuse water that is not drinkable for other activities that do not require drinkable water Water-efficient manufacturing

Water Conservation Water-efficient manufacturing Xeriscaping Reuse water for cooling or heating Xeriscaping Landscaping with drought-tolerant plants Runoff and rain collection Rain barrels collect water from hard surfaces