Chlorination of Harvested Rainwater: Comparison
View Latest Version
Please note this is a comparison between Version 3 by Fanny Huang and Version 2 by Fanny Huang.

 In many rural areas, primary water sources such as surface water and groundwater are at risk of contamination with rapid agricultural and industrial growth and climate change-related issues. Rainwater harvesting is an ancient practice for rural communities, and the momentum around its use is continually growing in recent years. Among the disinfection methods, chlorination is the most common method in large-scale water treatment schemes. It is also one of the most cost-effective water disinfection processes. It is further suggested that free chlorine could be extensively efficacious against most waterborne pathogens and cause destruction of the cell DNA of these microorganisms, except for Cryptosporidium parvum oocysts and Mycobacteria species. Consequently, this method could reduce waterborne diseases in many countries. In addition, chlorine tablets and liquid pool chlorine are reasonably accessible and safe for transportation to the end-users for residential purposes.

  • rainwater harvesting
  • water treatment
  • disinfection
  • chlorination
  • drinking water

1. Introduction

Clean water resources are under stress globally to meet growing demand. The rapid industrial and urban growths often cause water pollution [1,2][1][2]. Many industries in developing countries discharge untreated wastewater into surface water bodies [3,4][3][4]. Many primary water sources such as groundwater and surface water bodies in both developing and developed countries are exposed to various industrial and agricultural pollutants [5,6][5][6]. As a result, people suffer from cancer and other diseases, which are caused by water pollution among other factors [7,8,9][7][8][9]. In many rural areas, groundwater is either unavailable or contaminated (such as arsenic and fluoride contamination). Currently, 783 million people do not have access to clean water, and 84% of them live in rural areas of developing countries. Many rural communities have been suffering from various acute waterborne diseases such as hepatitis, cholera, dysentery, giardiasis, diarrhoea, typhoid, and cryptosporidiosis [10,11,12][10][11][12]. The water treatment cost is relatively high, and many developing countries cannot afford to treat polluted water [13]. In many locations, rural and low-income communities are deprived of the benefit of modern water treatment technologies [14].
To meet clean water demand, harvested rainwater (HRW) is getting more attention in remote and some urban areas as rainwater is generally fresh in nature [15,16,17,18,19][15][16][17][18][19]. A question is often raised whether HRW needs disinfection before human consumption. For example, Chubbaka et al. [20] identified that some households in South Australia prefer drinking untreated HRW; however, some residents treat HRW using a filtration system.
Research suggests that in many parts of the world, the quality of untreated HRW does not comply with the World Health Organisation’s (WHO) [20,21][20][21] drinking water guidelines. The reasons include (i) location of roof catchment [22], (ii) surrounding sources of pollutants [22], (iii) roof materials, (iv) air quality, (v) tank size, (vi) animal waste [23], and (vii) materials used in HRW storage and collection systems [24]. It indicates that at many instances HRW contains heavy metals [25], and microbiological contaminants. The consumption of untreated HRW for an extended period may have both immediate and long-term health consequences [21]. Therefore, HRW treatment at a small scale has become more relevant to the communities now than in the past.
Researchers indicate that the efficacy of water treatment methods may vary depending on the water source, environment, and catchment [26]. For example, Brown and Sobsey [27] conducted a test on the performance of ceramic filters between two types of water catchments, (a) rainwater and (b) surface water. They showed that rainwater has less turbidity compared to surface water. Lantagne et al. [28] proposed five well-known methods for household water treatment: (i) chlorination, (ii) filtration (bio-sand and ceramic), (iii) solar disinfection, (iv) combination of filtration and chlorination, and (v) combination of flocculation and chlorination. They noted that water quality improved significantly after treatment, reducing water-borne diseases. They also compared the performances of various filtration and disinfection methods as shown in Table 1.
Table 1. Performance analysis of various household water treatment methods [28,29,30,31,32][28][29][30][31][32].
Treatment Method Can Remove Virus Can Remove Bacteria Can Remove Protozoa Does the Treatment Method Has a Residual Effect Cost of Treatment Disinfection by Product Production Reference
Disinfection by Chlorination Yes—Medium Yes—high Yes—Low Yes US $0.09–0.37 per bottle of chlorine solution Yes [28]
Filtration by bio-sand Not known Yes—Medium to High Yes—High No - No [28]
Filtration by ceramic Not known Yes—High Yes—High No Water cost US $0.3–0.5

Filter cost US $2.5–4		 No [29,30][29][30]
Filtration and chlorination Yes—Medium Yes—High Yes—High Yes US $0.09–0.37 per bottle of chlorine solution Yes—Medium [28]
Disinfection by solar Yes—High Yes—High Yes—High No US $0, bottle cost not included No [28]
Flocculation and chlorination Yes—High Yes—High Yes—High Yes US $0.07 Yes [31]
Aeration + filtration + carbon filtration + ultra violet disinfection Yes—High Yes—High Yes—High Yes AUD

4.59/m3		 No [32]
Many non-governmentgovernment organisations (NGOs) have used hypochlorite solution for water disinfection at domestic level [32,33,34][32][33][34] because hypochlorite solution has additional advantages such as (i) lower cost, (ii) residual effect, and (iii) greater availability [34]. Among the advantages, the residual effect is one of the critical factors for hypo-chlorite solution, which can prevent stored water from potential recontamination. Ali et al. [35] noticed regrowth of coliform bacteria after treating water by coagulation. Therefore, it can be argued that there is a potential risk of recontamination of the disinfected rainwater while it is being stored. Hence, a hypochlorite solution could be an effective and preferred disinfectant for rainwater disinfection.
However, using the hypochlorite solution has some concerns that must be considered before recommending it for disinfecting HRW at the household level. Hypochlorite solution can produce disinfection byproducts (DBP) when it reacts with organic contents present in water [28,36][28][36]. HRW may contain organic matter, and hypochlorite solution can produce DBPs when applied to untreated rainwater [37]. DBP consumption through drinking water may trigger severe health issues like cancer [38]. Hence, both inadequate and excess chlorine dose in water treatment is undesirable. Raising awareness on microbiological contaminants and chlorine DBPs in HRW is essential to people who consume rainwater.

2. Water Quality of Harvested Rainwater (HRW): Secondary Data Analysis of Microbiological Contaminants

Bacteria, viruses, and protozoa are the major microbiological pollutants in HRW [39]. The primary sources of microbial contaminants are the faeces of animals such as birds, rats, squirrels, and possums [23]. These unwanted animal excrements are washed out from the roof and accumulated in rainwater tanks during rainfall. Figure 1 shows various harmful microorganisms in rainwater tank collected from 15 countries. Among the microbiological pollutants, faecal and total coliform have been identified in higher concentrations than E. coli and Enterococci. Figure 1 demonstrates that faecal and total coliform were found excessive in rainwater worldwide in both developed and developing countries. This indicates that rainwater treatment is mainly ignored on a small scale, irrespective of the country’s economic status.
Figure 1. Microbiological pollutants in harvested rainwater (HRW) in various countries [40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56].
WHO drinking water guidelines [57] suggest that drinking water must be free from E. coli, total coliform, and thermotolerant coliform bacteria. However, Figure 1 demonstrates that rainwater contains a substantial amount of these microbiological pollutants [21]. They are responsible for waterborne diseases such as Diarrhoea, Cholera, Typhoid, and long-term gastrointestinal disorders [58]. It was further noticed that less awareness and poor preventive control spread these diseases quickly across the community [59]. Figure 2 further explains human health damage while consuming untreated HRW. Diarrhoea and vomiting are the most common symptoms when waterborne diseases infect the body.
Figure 2. Microorganisms that are responsible for waterborne diseases.
Furthermore, remote communities are more vulnerable as they experience delays in having primary care services than large cities [60,61][60][61]. Therefore, the most viable solution to avert the spreading of disease in remote areas is to treat the rainwater and ensure water is clean and disinfected [59,62][59][62]. Therefore, it can be argued that untreated rainwater is not recommended to drink.

3. Opportunities for Hypochlorite Solution to Disinfect HRW

Among the disinfection methods, chlorination is the most common method in large-scale water treatment schemes [38,63,64,65][38][63][64][65]. It is also one of the most cost-effective water disinfection processes [66]. It is further suggested that free chlorine could be extensively efficacious against most waterborne pathogens and cause destruction of the cell DNA of these microorganisms, except for Cryptosporidium parvum oocysts and Mycobacteria species [66]. Consequently, this method could reduce waterborne diseases in many countries [32,47][32][47]. In addition, chlorine tablets and liquid pool chlorine are reasonably accessible and safe for transportation to the end-users for residential purposes [32].
Despite having some advantages, chlorination is not the preferred option in the residential or small-scale context [67,68][67][68]. Alekal et al. [67] and Burch and Thomas [29] identified three primary reasons which deter dwellers from implementing chlorination in their houses for water disinfection: (1) difficulties in mixing chemicals, (2) lack of convenience in storing chemicals, and (3) poor taste and odour issues because of incorrect dosing.

4. Chlorination for Disinfection

Various chlorine compounds are used for disinfection, such as chlorine gas, sodium-hypochlorite, chlorine tablets, calcium hypochlorite, bleaching powder, and chlorine dioxide [69,70][69][70]. The most common ones are (a) chlorine gas, (b) liquid pool chlorine (sodium hypochlorite, NaOCL) solution, and (c) calcium hypochlorite Ca(OCl)2 as solid [71]. When a chlorine-contained disinfectant is administered in water, it transforms into hypo-chlorous acid (HOCl) and hypochlorite ion (OCl−). Free available chlorine (FAC) is the combination of HOCl and OCl- in water [70,71][70][71]. The associated chemical reactions are shown in Equations (1)–(4):
Cl2 + H2O → HOCl + H+ + Cl−   
HOCl ⇆ H+ + OCl−   
Similarly, when NaOCL and Ca(OCl)2 are applied, they also form HOCl:
NaOCL + H2O → HOCl +NaOH   
Ca(OCl)2 + H2O → HOCl + Ca(OH)2   
Wei-Ling and Jensen [70] suggested total residual chlorine combines FAC and chloramine concentrations in water. FAC predominantly reacts with ammonia in water and forms mono-chloramine first and then dichloramine [70]. Also, FAC reacts with multiple substances available in water and influences chlorine demand [70].
Amy et al. [71] suggested hypochlorite ion is an active oxidising substance. Hypochlorite ion originated from the reversible ionisation process of (HOCl) as shown in Equation (2). However, HOCl performs better than OCl− against germs [71]. On the contrary, the unwanted microorganisms regrow in treated water after free chlorine fades out [72,73][72][73]. Amy et al. [63] stated hypochlorous acid is more stable if pH remains under 7.5; otherwise, it turns to OCl−. Amy et al. [63] further suggested that chlorination’s breaking point occurs when the total residual concentration remains unchanged.
Wei-Ling and Jensen [70] and Alim et al. [72] conducted tests on chlorine decay in laboratories, and they added chlorine and hypochlorite to water sample, respectively. They identified that total residual chlorine (TRC) dropped initially and increased later when chlorination proceeded further. When the chlorine dose exceeds the TRC, it indicates the breakpoint. Alim et al. [72] suggested that Sydney Water Corporation’s standard is to maintain chlorine levels between 1 and 3 mg/L. According to WHO [73] guidelines, chlorine contact time (CT) should be held at 15 mg. min/L for proper disinfection. That means the free chlorine residual must be kept more than 0.5 mg/L in the water for 30 min.

References

  1. Wang, Q.; Yang, Z. Industrial water pollution, water environment treatment, and health risks in China. Environ. Pollut. 2016, 218, 358–365.
  2. UNEP. A Snapshot of the World’s Water Quality: Towards a Global Assessment; United Nations Environment Programme: Nairobi, Kenya, 2016.
  3. Miao, Y.; Fan, C.; Guo, J. China’s water environmental problems and improvement measures. Environ. Resour. Econ. 2012, 3, 43–44.
  4. Ahmed, G.; Anawar, H.; Takuwa, D.; Chibua, I.; Singh, G.; Sichilongo, K. Environmental assessment of fate, transport and persistent behavior of dichlorodiphenyltrichloroethanes and hexachlorocyclohexanes in land and water ecosystems. Int. J. Environ. Sci. Technol. 2015, 12, 2741–2756.
  5. Haritash, A.; Kaushik, C.P.; Kaushik, A.; Kansal, A.; Yadav, A.K. Suitability assessment of groundwater for drinking, irrigation and industrial use in some North Indian villages. Environ. Monit. Assess. 2008, 145, 397–406.
  6. Schipper, P.; Vissers, M.; van der Linden, A.A. Pesticides in groundwater and drinking water wells: Overview of the situation in the Netherlands. Water Sci. Technol. 2008, 57, 1277–1286.
  7. Lu, Y.; Song, S.; Wang, R.; Liu, Z.; Meng, J.; Sweetman, A.J.; Jenkins, A.; Ferrier, R.C.; Li, H.; Luo, W. Impacts of soil and water pollution on food safety and health risks in China. Environ. Int. 2015, 77, 5–15.
  8. Lin, N.-F.; Tang, J.; Ismael, H.S.M. Study on environmental etiology of high incidence areas of liver cancer in China. World J. Gastroenterol. 2000, 6, 572.
  9. Ebenstein, A. The consequences of industrialization: Evidence from water pollution and digestive cancers in China. Rev. Econ. Stat. 2012, 94, 186–201.
  10. Rainbow, J.; Sedlackova, E.; Jiang, S.; Maxted, G.; Moschou, D.; Richtera, L.; Estrela, P. Integrated electrochemical biosensors for detection of waterborne pathogens in low-resource settings. Biosensors 2020, 10, 36.
  11. World Bank. Pakistan Strategic country Environmental Assessment; Main Report. Report 2006. Available online: https://elibrary.worldbank.org/doi/abs/10.1596/33928 (accessed on 17 July 2023).
  12. Cutler, D.; Miller, G. The role of public health improvements in health advances: The twentieth-century United States. Demography 2005, 42, 1–22.
  13. Jalan, J.; Ravallion, M. Does piped water improve child health for poor families in rural India? J. Econom. 2003, 112, 153–173.
  14. Jayaswal, K.; Sahu, V.; Gurjar, B. Water pollution, human health and remediation. In Water Remediation; Springer: Berlin/Heidelberg, Germany, 2018; pp. 11–27.
  15. Nasser Fava, N.d.M.; Terin, U.C.; Freitas, B.L.S.; Sabogal-Paz, L.P.; Fernandez-Ibañez, P.; Anthony Byrne, J. Household slow sand filters in continuous and intermittent flows and their efficiency in microorganism’s removal from river water. Environ. Technol. 2022, 43, 1583–1592.
  16. Alim, M.A.; Rahman, A.; Tao, Z.; Samali, B.; Khan, M.M.; Shirin, S. Suitability of roof harvested rainwater for potential potable water production: A scoping review. J. Clean. Prod. 2020, 248, 119226.
  17. Campisano, A.; Butler, D.; Ward, S.; Burns, M.J.; Friedler, E.; DeBusk, K.; Fisher-Jeffes, L.N.; Ghisi, E.; Rahman, A.; Furumai, H. Urban rainwater harvesting systems: Research, implementation and future perspectives. Water Res. 2017, 115, 195–209.
  18. Cook, S.; Sharma, A.; Chong, M. Performance analysis of a communal residential rainwater system for potable supply: A case study in Brisbane, Australia. Water Resour. Manag. 2013, 27, 4865–4876.
  19. Gurung, T.R.; Sharma, A. Communal rainwater tank systems design and economies of scale. J. Clean. Prod. 2014, 67, 26–36.
  20. Chubaka, C.E.; Ross, K.E.; Edwards, J.W. Rainwater for drinking water: A study of household attitudes. WIT Trans. Ecol. Environ. 2017, 216, 299–311.
  21. World Health Organization, Division of Operational Support in Environmental, Health. Guidelines for Drinking-Water Quality. Vol. 2, Health Criteria and Other Supporting Information: Addendum; World Health Organization: Geneva, Switzerland, 1998.
  22. Latif, S.; Alim, M.A.; Rahman, A. Disinfection methods for domestic rainwater harvesting systems: A scoping review. J. Water Process Eng. 2022, 46, 102542.
  23. Ahmed, W.; Hodgers, L.; Sidhu, J.P.; Toze, S. Fecal indicators and zoonotic pathogens in household drinking water taps fed from rainwater tanks in Southeast Queensland, Australia. Appl. Environ. Microbiol. 2012, 78, 219–226.
  24. Thomas, R.B.; Kirisits, M.J.; Lye, D.J.; Kinney, K.A. Rainwater harvesting in the United States: A survey of common system practices. J. Clean. Prod. 2014, 75, 166–173.
  25. Morrow, A.C.; Dunstan, R.H.; Coombes, P.J. Elemental composition at different points of the rainwater harvesting system. Sci. Total Environ. 2010, 408, 4542–4548.
  26. Zdeb, M.; Papciak, D.; Zamorska, J. An assessment of the quality and use of rainwater as the basis for sustainable water management in suburban areas. E3S Web Conf. 2018, 45, 00111.
  27. Brown, J.; Sobsey, M.D. Microbiological effectiveness of locally produced ceramic filters for drinking water treatment in Cambodia. J. Water Health 2010, 8, 1–10.
  28. Lantagne, D.S.; Quick, R.; Mintz, E.D. Household water treatment and safe: Storage options in developing countries. Navig 2006, 99, 17–38.
  29. Burch, J.D.; Thomas, K.E. Water disinfection for developing countries and potential for solar thermal pasteurization. Sol. Energy 1998, 64, 87–97.
  30. Van Halem, D.; Van der Laan, H.; Heijman, S.; Van Dijk, J.; Amy, G. Assessing the sustainability of the silver-impregnated ceramic pot filter for low-cost household drinking water treatment. Phys. Chem. Earth Parts A/B/C 2009, 34, 36–42.
  31. McAllister, S. Analysis and Comparison of Sustainable Water Filters; Department of Mechanical Engineering, Uiversity of Wisconsin: Madison, WI, USA, 2005.
  32. Lantagne, D.; Yates, T. Household water treatment and cholera control. J. Infect. Dis. 2018, 218 (Suppl. S3), S147–S153.
  33. Senevirathna, S.; Ramzan, S.; Morgan, J. A sustainable and fully automated process to treat stored rainwater to meet drinking water quality guidelines. Process Saf. Environ. Prot. 2019, 130, 190–196.
  34. Pickering, A.J.; Crider, Y.; Amin, N.; Bauza, V.; Unicomb, L.; Davis, J.; Luby, S.P. Differences in field effectiveness and adoption between a novel automated chlorination system and household manual chlorination of drinking water in Dhaka, Bangladesh: A randomized controlled trial. PLoS ONE 2015, 10, e0118397.
  35. Ali, S.I.; MacDonald, M.; Jincy, J.; Sampath, K.A.; Vinothini, G.; Philip, L.; Hall, K.; Aronson, K. Efficacy of an appropriate point-of-use water treatment intervention for low-income communities in India utilizing Moringa oleifera, sari-cloth filtration and solar UV disinfection. J. Water Sanit. Hyg. Dev. 2011, 1, 112–123.
  36. Villanueva, C.M.; Cordier, S.; Font-Ribera, L.; Salas, L.A.; Levallois, P. Overview of disinfection by-products and associated health effects. Curr. Environ. Health Rep. 2015, 2, 107–115.
  37. Keithley, S.E.; Fakhreddine, S.; Kinney, K.A.; Kirisits, M.J. Effect of treatment on the quality of harvested rainwater for residential systems. J. Am. Water Work. Assoc. 2018, 110, E1–E11.
  38. Mazhar, M.A.; Khan, N.A.; Ahmed, S.; Khan, A.H.; Hussain, A.; Changani, F.; Yousefi, M.; Ahmadi, S.; Vambol, V. Chlorination disinfection by-products in municipal drinking water—A review. J. Clean. Prod. 2020, 273, 123159.
  39. De Kwaadsteniet, M.; Dobrowsky, P.; Van Deventer, A.; Khan, W.; Cloete, T. Domestic rainwater harvesting: Microbial and chemical water quality and point-of-use treatment systems. Water Air Soil Pollut. 2013, 224, 1–19.
  40. Van der Sterren, M.; Rahman, A.; Dennis, G.R. Quality and quantity monitoring of five rainwater tanks in Western Sydney, Australia. J. Environ. Eng. 2013, 139, 332–340.
  41. Verrinder, G.; Keleher, H. Domestic drinking water in rural areas: Are water tanks on farms a health hazard? Environ. Health 2001, 1, 51–56.
  42. Spinks, A.T.; Dunstan, R.H.; Harrison, T.; Coombes, P.; Kuczera, G. Thermal inactivation of water-borne pathogenic and indicator bacteria at sub-boiling temperatures. Water Res. 2006, 40, 1326–1332.
  43. Despins, C.; Farahbakhsh, K.; Leidl, C. Assessment of rainwater quality from rainwater harvesting systems in Ontario, Canada. J. Water Supply Res. Technol. AQUA 2009, 58, 117–134.
  44. Sazakli, E.; Alexopoulos, A.; Leotsinidis, M. Rainwater harvesting, quality assessment and utilization in Kefalonia Island, Greece. Water Res. 2007, 41, 2039–2047.
  45. Albrechtsen, H.J. Microbiological investigations of rainwater and graywater collected for toilet flushing. Water Sci. Technol. 2002, 46, 311–316.
  46. Dillaha III, T.A.; Zolan, W.J. Rainwater catchment water quality in Micronesia. Water Res. 1985, 19, 741–746.
  47. Simmons, G.; Hope, V.; Lewis, G.; Whitmore, J.; Gao, W. Contamination of potable roof-collected rainwater in Auckland, New Zealand. Water Res. 2001, 35, 1518–1524.
  48. Uba, B.N.; Aghogho, O. Rainwater quality from different roof catchments in the Port Harcourt district, Rivers State, Nigeria. J. Water Supply Res. Technol.—Aqua 2000, 49, 281–288.
  49. Lee, J.Y.; Yang, J.-S.; Han, M.; Choi, J. Comparison of the microbiological and chemical characterization of harvested rainwater and reservoir water as alternative water resources. Sci. Total Environ. 2010, 408, 896–905.
  50. Pinfold, J.V.; Horan, N.J.; Wirojanagud, W.; Mara, D. The bacteriological quality of rainjar water in rural northeast Thailand. Water Res. 1993, 27, 297–302.
  51. Lye, D.J. Bacterial Levels In Cistern Water Systems Of Northern Kentucky 1. JAWRA J. Am. Water Resour. Assoc. 1987, 23, 1063–1068.
  52. Crabtree, K.D.; Ruskin, R.H.; Shaw, S.B.; Rose, J.B. The detection of Cryptosporidium oocysts and Giardia cysts in cistern water in the US Virgin Islands. Water Res. 1996, 30, 208–216.
  53. Lévesque, B.; Pereg, D.; Watkinson, E.; Maguire, J.S.; Bissonnette, L.; Gingras, S.; Rouja, P.; Bergeron, M.G.; Dewailly, E. Assessment of microbiological quality of drinking water from household tanks in Bermuda. Can. J. Microbiol. 2008, 54, 495–500.
  54. Al-Salaymeh, A.; Al-Khatib, I.A.; Arafat, H.A. Towards sustainable water quality: Management of rainwater harvesting cisterns in Southern Palestine. Water Resour. Manag. 2011, 25, 1721–1736.
  55. Abo-Shehada, M.N.; Hindyia, M.; Saiah, A. Prevalence of Cryptosporidium parvum in private drinking water cisterns in Bani-Kenanah district, northern Jordan. Int. J. Environ. Health Res. 2004, 14, 351–358.
  56. Handia, L.; Tembo, J.M.; Mwiindwa, C. Potential of rainwater harvesting in urban Zambia. Phys. Chem. Earth Parts A/B/C 2003, 28, 893–896.
  57. World Health Organization (WHO). Guidelines for Drinking-Water Quality: First Addendum to the Fourth Edition; World Health Organization: Geneva, Switzerland, 2017.
  58. Clasen, T.F.; Thao, D.H.; Boisson, S.; Shipin, O. Microbiological effectiveness and cost of boiling to disinfect drinking water in rural Vietnam. Environ. Sci. Technol. 2008, 42, 4255–4260.
  59. Clasen, T.F.; Alexander, K.T.; Sinclair, D.; Boisson, S.; Peletz, R.; Chang, H.H.; Majorin, F.; Cairncross, S. Interventions to improve water quality for preventing diarrhoea. Cochrane Database Syst. Rev. 2015, 10.
  60. Young, L.; Peel, R.; O’Sullivan, B.; Reeve, C. Building general practice training capacity in rural and remote Australia with underserved primary care services: A qualitative investigation. BMC Health Serv. Res. 2019, 19, 338.
  61. Lawal, O.; Anyiam, F.E. Modelling geographic accessibility to primary health care facilities: Combining open data and geospatial analysis. Geo-Spat. Inf. Sci. 2019, 22, 174–184.
  62. Fewtrell, L.; Kaufmann, R.B.; Kay, D.; Enanoria, W.; Haller, L.; Colford Jr, J.M. Water, sanitation, and hygiene interventions to reduce diarrhoea in less developed countries: A systematic review and meta-analysis. Lancet Infect. Dis. 2005, 5, 42–52.
  63. Mintz, E.; Bartram, J.; Lochery, P.; Wegelin, M. Not just a drop in the bucket: Expanding access to point-of-use water treatment systems. Am. J. Public Health 2001, 91, 1565–1570.
  64. Sobsey, M.D.; Water, S.; World Health Organization. Managing Water in the Home: Accelerated Health Gains from Improved Water Supply; World Health Organization: Geneva, Switzerland, 2002.
  65. Zlatanović, L.; van der Hoek, J.P.; Vreeburg, J. An experimental study on the influence of water stagnation and temperature change on water quality in a full-scale domestic drinking water system. Water Res. 2017, 123, 761–772.
  66. Sobsey, M.D. Inactivation of health-related microorganisms in water by disinfection processes. Water Sci. Technol. 1989, 21, 179–195.
  67. Alekal, P.; Baffrey, R.; Franz, A.; Loux, B.; Pihulic, M.; Robinson, B.; Young, S.; Murcott, S. Decentralized Household Water Treatment and Sanitation Systems; Massachusetts Institute of Technology: Cambridge, MA, USA, 2005; p. 38.
  68. Andreoli, F.; Sabogal-Paz, L. Household slow sand filter to treat groundwater with microbiological risks in rural communities. Water Res. 2020, 186, 116352.
  69. Metcalf Eddy, I. Wastewater Engineering: Treatment and Reuse, 4th ed.; Tchobanoglous, G., Franklin, L., Burton, H., David, S., Eds.; McGraw-Hill: Boston, MA, USA, 2003.
  70. Wei-Ling, C.; Jensen, J.N. Effect of chlorine demand on the ammonia breakpoint curve: Model development, validation with nitrite, and application to municipal wastewater. Water Environ. Res. 2001, 73, 721–731.
  71. Amy, G.; Bull, R.; Craun, G.F.; Pegram, R.; Siddiqui, M.; World Health Organization. Disinfectants and Disinfectant By-Products; World Health Organization: Geneva, Switzerland, 2000.
  72. Alim, M.A.a.; Ashraf, A.A.; Rahman, A.; Tao, Z.; Roy, R.; Khan, M.M.; Shirin, S. Experimental investigation of an integrated rainwater harvesting unit for drinking water production at the household level. J. Water Process Eng. 2021, 44, 102318.
  73. WHO. Guidelines for Drinking-Water Quality, 2nd ed.; Surveillance and Control of Community Supplies; WHO: Geneva, Switzerland, 1997; Volume 3.
More
© Text is available under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/)
Video Production Service
Feedback