Joe Brown (LSHTM ) & Mark Sobsey (UNC) j oe.brown@lshtm.ac.uk , sobsey@email.unc

1. Household water treatment technology performance evaluation: emerging WHO guidelines and review of current technologies Joe Brown (LSHTM) & Mark Sobsey (UNC) joe.brown@lshtm.ac.uk, sobsey@email.unc.edu 6 November 2010, Atlanta ASTMH

2. Outline • Technology selection and microbiological effectiveness as a piece of the puzzle • WHO goals in creating this document • How we envision this guidance could be used • Approach to setting performance targets • General principles • Derivation of tiered system • Testing protocols • Context in the world of HWT

3. Which technology is the best? • It’s complicated • It depends on the context • It depends on your point of view • No easy answers here

4. HWT technology selection/choice Implementers, NGOs • Sustained, correct use by users • Cost • Effectiveness in reducing microbes/chemicals • Demonstrated health impacts • Other factors • Users • Acceptability and accessibility, user friendliness • Cost • Aesthetic qualities • Delivery of clean, good tasting water that is healthier & “better” than other sources • Other factors

5. Why does effectiveness matter? • HWT is intended specifically to reduce pathogenic microbes in water • No feedback mechanism available to most users • Links with public health impact, which is the point of HWT

6. WHO goals • Protect users, promote public health • Provide sector guidance • Useful international performance benchmarking • Advantages over other international protocols (but not intended to replace or supercede others) • Implementers, NGOs, private sector, individual users, government, etc • Create a flexible framework that is adaptable in national verification/certification programmes • Encourage development and use of more effective technologies

7. Primary audiences of document • (i) national-level certification organizations; • (ii), regulatory authorities; • (iii), those involved in developing and evaluating technologies, including universities and researchers; and • (iv), manufactures and implementers of small-scale water treatment technologies

8. Interpretation • Regulatory agencies or national authorities can interpret these guidelines and apply them to specific situations of local relevance in regard to water quality and/or treatment technologies. • The underlying principles forming the basis for this document are those set forth in the GDWQ, and may be applied where appropriate in product certification, pre-intervention performance evaluation, or technology selection

9. www.who.int

10. Guiding principles • Technologies should be as effective as possible against all classes of microbes: bacteria, viruses, protozoa • Technologies that do not meet the WHO recommended risk-based target from the Guidelines for Drinking-water Quality (10-6DALYs per person per year) may still contribute to reduction in waterborne disease risk • Technologies that do not consistently reduce all classes of microbial pathogens to a minimum extent should be recommended with caution • Technologies that are supported by epidemiological evidence of positive health impacts should continue to be recommended for use • Assessing microbiological effectiveness is an important part of technology selection • Microbiological performance is not relevant if the technology is not used

11. Approach • Assumptions for background water quality are used where no extensive and locally relevant data are available • Use of quantitative microbial risk assessment (QMRA) models • Recommended levels of performance are calculated

12. Background water quality data • These guidelines use published data on reference pathogens as assumed “background” water quality data • Reference pathogens: Campylobacter jejuni, rotavirus, Cryptosporidium • Dose-response risk models used to then calculate how effective technologies must be to reduce disease risk • Local data may be used but usually not practical

14. Computation of log ( and %) reduction of microbes to achieve risk targets

15. Log10 reduction values (LRVs) • 1 log10 = 90% reduction, 2 log10 = 99%, 3 log10 = 99.9%, 4 log10 = 99.99%, and so on • Major outcomes from testing • Standard metric for technology performance under challenge conditions • Calculated from log10 concentrations of microbes observed in untreated/treated water • Provides a comparative basis for technology selection

16. LRV required based on untreated water quality Table 7.3, GDWQ

18. Typical longitudinal water quality data

19. Risk threshold

20. Risk threshold may be lower for some groups

21. 153 high risk days

22. 90% reduction, 103 high risk days

23. 99% reduction, 39 high risk days

24. 99.9% reduction, 4 high risk days

25. 99.99% reduction, 1 high risk day

26. 99.999% reduction, 0 high risk days

27. Why the pursuit of greater performance then? • Modest microbial reductions can prevent disease, sometimes dramatically • Basis for the “minimally protective” tier • Higher risk waters and outbreak situations are the “design case” for HWT: these situations require a more effective barrier • Emergency use • Water quality can change rapidly and new risks can arise • The highest tier, “most protective”, meets WHO risk-based target for drinking water quality

29. Guiding principles for technology-specific testing protocols • Protocols should result in data that demonstrate effectiveness of HWT technologies against bacteria, viruses, and protozoa. • Different technologies require different approaches to demonstrating performance. • Protocols should be rigorous but flexible. Options should exist to enable protocols to be adapted to new technologies, alternative test microbes, and different contexts, as long as scientifically credible evidence is the result. • Laboratory testing should closely model actual field use. • Protocols should be locally developed or adapted. • Protocols should be accompanied by an appropriate institutional framework.

30. Recommended protocols • Technology specific and flexible • May be based on local capabilities and resources • Based on actual field use conditions • Intended to capture life cycle of longer-use technologies • Microbes and low-cost methods are now accessible to a reasonably equipped lab anywhere in the world • Spike in microbes to challenge waters • Assay influent and effluent water, approximating use conditions and cycle of use for technology • Log10 reductions are calculated: • LRV = log10(Cuntreated/Ctreated)

31. Where do HWT technologies stand now? Sources: Souter et al. 2003, Lantagne 2001, Sobsey 2002, Hijnen et al. 2004, Timms et al., Kaiser et al. 2002, Colwell et al. 2003, Huq et al. 1996, Logsdon 1990, Schuler et al. 1988, NAP 1997, Sobsey 1989, Batchley and Peel 2001, Walker et al. 2004, Meyer and Reed 2001, Reed 1996, Wegelin et al. 1994, Mendez-Hermida et al. 2005, CDC 2001, CDC.gov 2005, Brown and Sobsey 2005, Sobsey and Brown 2006.

32. Next steps for this effort • Public comment period • Publication