Multidisciplinary Research Week 2013

World Water Day: Water Cooperation

‘Water quality: addressing global problems at source’,

by Dr Jim Wright, Geography and Environment, University of Southampton.

Water quality: addressing global problems at source

Dr. Jim Wright,Geography and EnvironmentUniversity of Southampton

The Millennium Development Goal

Target 7C:

‘Halve, by 2015, the proportion of the population without sustainable access to safe drinking water and basic sanitation’

http://www.un.org/millenniumgoals/

Millennium Development Goal for Water – Met?

NEW YORK/GENEVA, 6 March 2012 – The world has met the MillenniumDevelopment Goal (MDG) target of halving the proportion of people withoutsustainable access to safe drinking water, well in advance of the MDG 2015deadline, according to a report issued today by UNICEF and the World HealthOrganization (WHO). Between 1990 and 2010, over two billion people gained accessto improved drinking water sources, such as piped supplies and protected wells.

United Nations Secretary-General Ban Ki-moon said, “Today we recognize a greatachievement for the people of the world. This is one of the first MDG targets to bemet….”

(http://www.wssinfo.org/)

The Joint Monitoring Programme (JMP) classification of improved (safe) and unimproved (unsafe) source types

(http://www.wssinfo.org/definitions-methods/watsan-ladder/)

Source class Types of source included

Improved: Piped into dwelling, plot, or yard Piped water connection located inside the user’s

dwelling, plot, or yard.

Improved: other sources Public taps or standpipes, tube wells or

boreholes, protected dug wells, protected

springs, or rainwater collection.

Unimproved drinking water sources Unprotected dug well, unprotected spring, cart

with small tank/drum, surface water (river,

dam, lake, pond, stream, canal, irrigation

channels), and bottled water.

Photo: Jim Wright

Rapid Assessment of Drinking Water Quality (RADWQ)

Nationally representative sampling of water as consumed

Cr0ss-sectional Parameters of major public health concern

Thermotolerant coliforms Arsenic Fluoride nitrate

Rapid Assessment of Drinking Water Quality (RADWQ)

a. Tajikistan is based on 1995 data and that Jordan estimates for 2008 are the same as 1990 except for (i) where it is 1% lower.

(Bain, et al., Bulletin of the World Health Organization 90:228–235A, 2012)

A comparison of 1990 baseline, 2008 coverage and progress towards 2015 targets based on (i) access to improved sources, as published by JMP (ii) improved and ‘microbially compliant’ sources as adjusted using the RADWQ and (iii) improved and ‘overall compliant’ sources for five countries.

Quality – safety and aesthetics Available – quantity and continuity Affordable Accessible

Non-discriminatory Collection time

Sustainable – environmental, financial, organisational

Equitable

Dimensions of safe water access

(The Millennium Development Goals Report 2011)

Socio-economic inequality in safe water access

Peruvian piped water users

(Yang, et al., Environmental Science & Technology 47: 1222-1230, 2013)

Bangladeshi tubewell users

(Yang, et al., Environmental Science & Technology 47: 1222-1230, 2013)

Water testing in remote locations

Source: Ince et al (2010)

Photo: Melissa Loudon, University of Cape Town

Photo: Melissa Loudon, University of Cape Town

Studies of diagnostic accuracy

E. coli or thermotolerant coliform test result

H2S test result Positive Negative

Presenttrue positive

(tp)false positive

(fp)

Absentfalse negative

(fn)true negative

(tn)

Literature review: search terms

Terms for H2S test(e.g. hydrogen sulphidehydrogen sulfidePathoscreen, H2S)

Terms for water samples

(water)

Terms for standard tests(e.g. fecal coliform

faecal coliformthermotolerant coliform

E. Coli)

Literature Review: Results

(Wright et al. Tropical Medicine and International Health 17: 94-105, 2012)

How does H2S test typically perform?

In B, the three crosses in the top left corner represent the sensitivities and specificities of a. Colilert (Edberg et al., 1988), b. Colitag (NEMI, 2009), c. Colisure (McFeters et al., 1995).

(Wright et al. Tropical Medicine and International Health 17: 94-105, 2012)

Contamination rates are important

1: Source – Wright et al, 2012; 2: Source – (Ince et al. 2006); 3: Source – (Ince et al. 2006)

Lab test result

H2S test result Present Absent

Positive 191 36

Negative 29 244

Total 220 280

H2S test sensitivity1 0.87

H2S test specificity1 0.82

Water source contamination rate (from RADWQ Survey)2 44%

H2S test positive predictive value 0.84

True positives False positives

Contamination rates are important

1: Source – Wright et al, 2012; 2: Source – (Ince et al. 2006); 3: Source – (Ince et al. 2006)

Lab test result

H2S test result Present Absent

Positive 26 61

Negative 4 409

Total 30 470

H2S test sensitivity1 0.87

H2S test specificity1 0.82

Water source contamination rate (from RADWQ Survey)2 6%

H2S test positive predictive value 0.30

True positives False positives

False positives & source contamination

gre

en /

(g

reen +

pin

k)

(Wright et al. Tropical Medicine and International Health 17: 94-105, 2012)

Existing H2S method very cheap…. …but variable accuracy

Evaluate before use Caution needed with such tests where

contamination uncommon Other alternatives:

Aquatest device DelAgua

Conclusions

Although target 7c met, still substantial population without safe water access

Field diagnostics for remote areas could contribute to Measuring safe water access Remediating unsafe sources

Requires a multi-disciplinary approach

Conclusions

Acknowledgements

Particular thanks to Rob Matthews - University of BristolAquatest consortium:Prof. Stephen Gundry, Rob Bain, Rob Matthews - University of BristolDr. Hong Yang – University of SouthamptonProf. Jamie Bartram, Rob Bain – University of North CarolinaDr. Steve Pedley, John Elliott – University of SurreyDr. Kate Walker – London School of Hygiene and Tropical MedicineProf. Ulrike Rivett, Melissa Loudon – University of Cape Town

Funding:This research has been funded by the Bill & Melinda GatesFoundation, under a grant to the University of Bristol,whose purpose is to develop a low-cost test of waterquality for use in developing countries.

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World Water Day: Water CooperationMultidisciplinary Research Week 2013