POTABLE REUSE: When Are We Going to Drink It?

Bahman SheikhApril 28, 2010

Drinking Water from Wastewater

Presentation Outline

• Evolution of Water Recycling• Direct or Indirect?• Who Is Drinking Recycled Water?• Who Failed to Implement Potable Reuse• Advantages of Potable Reuse• Energy Use, Cost Comparisons• Obstacles to Potable Reuse• What Are We Waiting For?

Evolution of Water Reuse:

to Direct Potable Reuse

to Indirect Potable Reuse

toGroundwater Recharge 

to Industrial Reuse

to Landscape Irrigation

FromAgricultural Reuse

Crops Grown with Recycled Water76%

1.0%

1.8%2.3%

4.8%1.1%

ArtichokesStrawberries

Lettuce

CeleryBroccoliCauliflower

Israel, Dan Region Project 

Direct or Indirect

• Definitions• Water Quality Differences

– Direct; Nearly Pure Water– Indirect; Blended with Runoff, Groundwater

• Role of the Environmental Buffer– Psychological‐‐– Regulatory– Technological

• Storage• Quality Control

• Which Will It Be?

On‐Going Successful Potable Reuse

• Unplanned Potable Reuse• Windhoek• Alexandria, Virginia• Singapore• Orange County Groundwater Replenishment• Los Angeles County Seawater Intrusion Barriers• El Paso, Texas• Chanute, Kansas 1956‐57• Denver DPR Demonstration  Study  1985‐88

Sources:   California Department of Water Resources, 2005  Colorado River Salinity Control Forum, October 2005Indirect Potable Reuse—Unplanned

Orange County 

Silverado

400 ft. Gravel

Pico Formation (“bedrock”)

200 ft. Sand Aquifer

Oce

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Paci

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Hw

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Modified from DWR 1961, Cross Section E-E’

West EastGENERALIZED CROSS SECTION OF AQUIFERS

Merged Silverado & 400 ft Gravel Aquifers

Groundwater Flow Inland due to Basin Pumping

Lower San Pedro Aquifer

App

rox.

100

0 fe

et

Seawater Intrusion Barriers

Failed Potable Reuse Projects

• San Diego “Repurified Water”– Senatorial Candidate’s Populism– “Toilet‐to‐Tap”– “Effluent of the Affluent”

• City of Los Angeles “East Valley Project”– Mayoral Candidate’s Demagoguery– San  Fernando Valley Separatist Movement

• Livermore “Pure Water Revival”– Anti‐Growth Opposition– Disingenuous Water Quality Claims

Advantages of Potable Reuse• Lower Distribution System Costs• Higher Water Quality

– Removal of Microconstituents (also called CECs)– Removal of Salts– Improvement of Existing Water Sources

• Greater Reliability of Supply Resource• Stoppage of Effluent Discharge to Environment

Obstacles to Potable Reuse

• Public Perception– Alternative Supplies– Costs– Water Quality– “Yuck” Factor

• Political Will• Up‐Front Costs• Regulatory Hurdles• “Unknowns”

Cost Comparisons6543210

kWh/m

3

Reverse Osmosis Cost Trends

0

1

2

3

4

5

1950 1960 1970 1980 1990 2000

Year

$/cu

bic

met

er

Reverse Osmosis Technology

Micro Filtration

Bacteria

Pathogens

Virus

SaltWater

Water

Reverse Osmosis

What Are We Waiting for?• The Right Time Is NOW!

– We Have the Technology– The Price Is Right– Our Mindset Is Not There Yet

• Political Will Is Lacking• Perceptions Are Out of Touch with Reality

– Public Education– Getting Over the Fear Factor

• Crisis Atmosphere Would Push Potable Reuse– Drought (Atmospheric, Legal, Climate Change)– Population Explosion– Competing Demands for Water