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Does Clean Water Make You Dirty

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Jeff van Geete
Jeff van Geete

Bennett examines whether access to clean water reduces incentives for sanitation in Cebu, Philippines. Using panel data from 1983-2005, he finds: 1) A negative correlation between piped water access and sanitation levels, suggesting water and sanitation may be substitutes as clean water allows people to endure dirtier environments. 2) Increased diarrhea is associated with community access to piped water, consistent with reduced sanitation efforts. However, household access is linked to less diarrhea. 3) Instrumental variable models exploiting topological characteristics correlated with water access but not sanitation still find evidence that piped water reduces sanitation and increases diarrhea, indicating a causal relationship. 4) A robustness check

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DoesCleanWaterMakeYouDirty? WaterSupplyandSanitationinthePhilippines JournalofHumanResources(2012) DanBennett,HarrisSchoolofPublicPolicyStudiesatUniversityofChicago Presented by: Jeff van Geete
Do behavioral responses undercut the expected health benefits of clean water provision? Research Question
Consider a simple health production model: yi =ai +B1X+B2Y+ci Ifunivariateregression oneitherXorYresultsin apositivecoefficient, whywouldoneofthe abovecoefficients be negative? Answer: Clean water and sanitation may be substitutes if clean water enables the recipient to endure a dirtier environment without sacrificing health. Households also may face a budgetary tradeoff between sanitation and water. Although the degree of substitutability between these inputs may vary by setting, clean water and sanitation are negatively correlated in the present context of Cebu.
Previous Literature Clean water seems beneficial in some contexts but ineffective or even harmful in others (Fewtrell et al. 2005) Kremer and Miguel (2004, 2007) find positive externalities for school attendance and social learning about the benefits of a deworming program. Kremer et al. (2007) find a marginally significant health impact of spring protection in rural Kenya. Lipscomb and Mobarak (2008) examine the impact of political decentralization on pollution spillovers in Brazil (shirking). Lakdawalla, Sood, and Goldman (2006) argue that antiretroviral drugs encourage risky sexual behavior (shirking).
Motivations & Limitations In an effort to internalize the externality, the community may invoke social norms or other strategic mechanisms that lead to a sanitation complementarity (Ostrom 2000; Bandiera, Barankay, and Rasul 2005; Banerjee, Iyer, and Somanathan 2006). Bennett draws much of his motivation from Peltzmans shirkers (1975) and Akerlofs social norms (1980) Causal mechanism relies on strategic interactions Like Fisman and Miguels (2007) Norms paper, only parking fines are replaced by the costs of keeping clean in a dirty environment.
Setting Metro CebuWater District (MCWD) delivers chlorinated piped water to ~40 % of area households 110 high volume deep wells, which are located inland from the city, stores water in several area reservoirs $86 for installation, $2.70 per month for a half-inch connection, and $0.30 ( vs. $0.65 in Denver) per cubic meter of water. This fee schedule subsidizes poor households - community well A household is defined as having piped water if the MCWD is its usual main source of drinking water Cebu lacks a centralized sewer system (500T of public defecation)
Data N = 3,000HH, 22 yrs Source:CLHNS Why not just compare means? Water prevalence maybe endogenousto sanitation Cebu Longitudinal Health and Nutrition Survey (CLHNS): Panel survey of ~3,000 households over 22 years; includes all households that experienced a birth from June 1983-May 1984 in 33 randomly selected barangays (out of 79 inCebu, ~42k total). 74 percent barangays that are designated as urban. Surveyors conducted 12 bimonthly interviews with each household from 1983 to 1985, and followed up five additional times from 1991 to 2005 As a panel survey, the CLHNS captures a sample that is relatively young in early rounds and old in late rounds. fertility-selected sampling methodology (children CLHNS lacks reliable measures of income or monetary wealth Data on diarrhea only from the 12 bimonthly surveys, 198385 Collapsed into a 12-period count variable for anyone in the HH having diarrhea in the last week.
How does Bennett help us answer the research question? i substitutes water and sanitation but different is have complementary sanitation An individuals health-maximization problem defines his/her best response functions: Through the implicit function theorem, the first order condition for sanitation yields the partial effect of clean water on sanitation: Which lets us sign the effects of interest:
Comparative static models give predictions }Driving mechanism Health Responses Endogeneity of piped water }Robustness Check (SoilThickness)
Table 1: Different onObservables si = {0,1} measuredby surveyors fromMCWD
Piped water prevalence at years of survey
Negative correlation between piped water and sanitation
Positive correlation between piped water and self- reported diarrhea probably a good thing!* (* Unless substitution manifests as shirking!)
Table 2: _ 6% worse sanitation response from a movement of 1 SD (0.34) in wi
Table 3 sd(w) = 0.27 but 8% more diarrhea associated with community clean water usage. Consistent with s complementarity 9% less diarrhea associated with household clean water usage sd(w) = 0.51 (?) _
Makinga super instrument Pipedwaterandsanitation wouldbeendogenousifdirtier placesconsumemorewater FromEq11(Table2) Cov(wi,ei) O recovervariationusing topologicalcharacteristics correlatedwithaccesstopiped water,uncorrelatedwiths(ER)
Table 4: First-stage: w = ai+zi+ei Second-stage: si = ai+ B1w+B2X+ei _ ^
Table 6: SoilThickness (arobustnesscheck) 28% more diarrhea for thickest soil sd(T) = 0.53 (?) 10-13% lower sanitation at thickest soil
Take-away / Conclusion To our understanding of sanitations complementary effects, Bennett adds those substitutive effects at the household level which may constrain our expected returns from investment in developing nations. Akerlof (1980) describes how a social norm may induce a large strategic complementarity. Compliance with a social norm strengthens the norm, which encourages greater compliance. One explanation for Bennets findings is that clean water has interfered with a social norm of sanitation. For some, the sanitation benefits of shirking outweigh those from adherence to norms. Clean water recipients were cleaner without clean water
Bonus: Table 5 - Placebo Education,likehealth,isan investmentinhumancapital preferencesandSES aredeterminantsofboth Doeseducationrespondto cleanwater? No(wedontwantitto)

More Related Content

Does Clean Water Make You Dirty

  • 2. Do behavioral responses undercut the expected health benefits of clean water provision? Research Question
  • 3. Consider a simple health production model: yi =ai +B1X+B2Y+ci Ifunivariateregression oneitherXorYresultsin apositivecoefficient, whywouldoneofthe abovecoefficients be negative? Answer: Clean water and sanitation may be substitutes if clean water enables the recipient to endure a dirtier environment without sacrificing health. Households also may face a budgetary tradeoff between sanitation and water. Although the degree of substitutability between these inputs may vary by setting, clean water and sanitation are negatively correlated in the present context of Cebu.
  • 4. Previous Literature Clean water seems beneficial in some contexts but ineffective or even harmful in others (Fewtrell et al. 2005) Kremer and Miguel (2004, 2007) find positive externalities for school attendance and social learning about the benefits of a deworming program. Kremer et al. (2007) find a marginally significant health impact of spring protection in rural Kenya. Lipscomb and Mobarak (2008) examine the impact of political decentralization on pollution spillovers in Brazil (shirking). Lakdawalla, Sood, and Goldman (2006) argue that antiretroviral drugs encourage risky sexual behavior (shirking).
  • 5. Motivations & Limitations In an effort to internalize the externality, the community may invoke social norms or other strategic mechanisms that lead to a sanitation complementarity (Ostrom 2000; Bandiera, Barankay, and Rasul 2005; Banerjee, Iyer, and Somanathan 2006). Bennett draws much of his motivation from Peltzmans shirkers (1975) and Akerlofs social norms (1980) Causal mechanism relies on strategic interactions Like Fisman and Miguels (2007) Norms paper, only parking fines are replaced by the costs of keeping clean in a dirty environment.
  • 6. Setting Metro CebuWater District (MCWD) delivers chlorinated piped water to ~40 % of area households 110 high volume deep wells, which are located inland from the city, stores water in several area reservoirs $86 for installation, $2.70 per month for a half-inch connection, and $0.30 ( vs. $0.65 in Denver) per cubic meter of water. This fee schedule subsidizes poor households - community well A household is defined as having piped water if the MCWD is its usual main source of drinking water Cebu lacks a centralized sewer system (500T of public defecation)
  • 7. Data N = 3,000HH, 22 yrs Source:CLHNS Why not just compare means? Water prevalence maybe endogenousto sanitation Cebu Longitudinal Health and Nutrition Survey (CLHNS): Panel survey of ~3,000 households over 22 years; includes all households that experienced a birth from June 1983-May 1984 in 33 randomly selected barangays (out of 79 inCebu, ~42k total). 74 percent barangays that are designated as urban. Surveyors conducted 12 bimonthly interviews with each household from 1983 to 1985, and followed up five additional times from 1991 to 2005 As a panel survey, the CLHNS captures a sample that is relatively young in early rounds and old in late rounds. fertility-selected sampling methodology (children CLHNS lacks reliable measures of income or monetary wealth Data on diarrhea only from the 12 bimonthly surveys, 198385 Collapsed into a 12-period count variable for anyone in the HH having diarrhea in the last week.
  • 8. How does Bennett help us answer the research question? i substitutes water and sanitation but different is have complementary sanitation An individuals health-maximization problem defines his/her best response functions: Through the implicit function theorem, the first order condition for sanitation yields the partial effect of clean water on sanitation: Which lets us sign the effects of interest:
  • 9. Comparative static models give predictions }Driving mechanism Health Responses Endogeneity of piped water }Robustness Check (SoilThickness)
  • 10. Table 1: Different onObservables si = {0,1} measuredby surveyors fromMCWD
  • 13. Positive correlation between piped water and self- reported diarrhea probably a good thing!* (* Unless substitution manifests as shirking!)
  • 14. Table 2: _ 6% worse sanitation response from a movement of 1 SD (0.34) in wi
  • 15. Table 3 sd(w) = 0.27 but 8% more diarrhea associated with community clean water usage. Consistent with s complementarity 9% less diarrhea associated with household clean water usage sd(w) = 0.51 (?) _
  • 17. Table 4: First-stage: w = ai+zi+ei Second-stage: si = ai+ B1w+B2X+ei _ ^
  • 18. Table 6: SoilThickness (arobustnesscheck) 28% more diarrhea for thickest soil sd(T) = 0.53 (?) 10-13% lower sanitation at thickest soil
  • 19. Take-away / Conclusion To our understanding of sanitations complementary effects, Bennett adds those substitutive effects at the household level which may constrain our expected returns from investment in developing nations. Akerlof (1980) describes how a social norm may induce a large strategic complementarity. Compliance with a social norm strengthens the norm, which encourages greater compliance. One explanation for Bennets findings is that clean water has interfered with a social norm of sanitation. For some, the sanitation benefits of shirking outweigh those from adherence to norms. Clean water recipients were cleaner without clean water
  • 20. Bonus: Table 5 - Placebo Education,likehealth,isan investmentinhumancapital preferencesandSES aredeterminantsofboth Doeseducationrespondto cleanwater? No(wedontwantitto)

Editor's Notes

  • #6: Across various specifications, sanitation is uncorrelated with piped-water usage of the household but is strongly negatively correlated with usage by the community
  • #9: Health is increasing and concave in clean water, wi>=0, and the sanitation of both households, si>=0 and s-i>=0. By inserting s-i into the health production function of household i, I explicitly incorporate a sanitation externality. Because the denominator is negative (H is concave), the degree of complementarity between wi and si signs this expression.
  • #10: The households sanitation response to its own water supply indicates the complementarity or substitutability of clean water and sanitation. The sanitation response to the water supply of others reflects both this interaction and the degree of sanitation complementarity across neighbors. An extension of the model considers the sanitation and health impacts of soil thickness, which similarly protects the household from unsanitary conditions.
  • #11: Columns 1 and 2, which split the sample according to mean piped water prevalence (0.306), demonstrate that obvious confounders cannot drive the relationship between clean water and sanitation. Households in high prevalence areas have two additional years of schooling and 26 percent fewer domesticated animals. They also have fewer young children, live in more robust housing, and have greater access to toilets or latrines. These observable characteristics suggest that communities with clean water should exhibit better sanitation and health. Columns 3 and 4 illustrate a similar point by comparing the first and last survey rounds. Piped water prevalence grew by 18 percent from 1983 to 2005. Although trends in household characteristics ostensibly encouraged sanitation, this outcome fell by 8 percent over the period.