Abstract

The current study aimed to assess the microbial quality of municipal (tap) and ground (borehole) water in Karachi, Pakistan. A health survey was also conducted to assess possible health risks of the drinking water. Fifty water samples (n = 25 each of tap and ground water) were collected from various locations of five administrative districts of Karachi for bacteriological analysis. In addition, a survey was conducted to assess the impact of drinking water on the health of city residents. Microbiological analysis results showed the presence of total coliform in 48 out of 50 (96%) tested samples. The total viable plate count at 37 °C was >200 CFU/ml in the majority of the collected samples which exceeded the permissible limit set by the World Health Organization (WHO) and the Pakistan Environmental Protection Agency. To evaluate the health risk of contaminated water, a total of 744 residents were interviewed. The information acquired from this field work revealed a high prevalence of waterborne diseases in the order of diarrhea and vomiting > skin problems > malaria > prolonged fever > eye problems and jaundice. To solve water and environmental problems, awareness and regular monitoring programs of water management and safe disposal of waste have been suggested.

INTRODUCTION

Background

Safe water for drinking purposes is a basic human right and provision of safe drinking water is one of the key objectives of sustainable development goals (Griggs et al. 2013). Waterborne diseases are one of the critical public health problems globally that are largely preventable. Many waterborne illnesses arise mainly due to the lack of clean water for drinking and cooking purposes, whereas others are spread by poor sanitation and personal hygiene practices (Bain et al. 2014; Deshmukh et al. 2016). There are multiple hazards that can contaminate water, but the physical, chemical and biological health hazards are the main ones (WHO 2011). However, microbiological quality of water is the most important aspect with respect to waterborne diseases (Bain et al. 2014).

Safe drinking water supply in Pakistan

Unfortunately, most of the developing countries fail to provide safe drinking water to their citizens, which leads to an increased burden of infectious diseases in these parts of the world (Van Leeuwen 2000). In Pakistan, provision of safe drinking water, sanitation and hygiene are becoming serious public health issues (Daud et al. 2017).

According to a recent study, an estimated 21 million people in Pakistan do not have access to safe water (WaterAid 2018). Moreover, diarrheal diseases caused by unsafe water and poor sanitation are the leading cause of mortality in infants and children in Pakistan (Rahman et al. 2014). The major cities of Pakistan are facing the dilemma of both water scarcity and lack of clean drinking water. Karachi, the coastal megacity in southern Pakistan, is no exception (Memon et al. 2011).

LITERATURE REVIEW

Since microbiological quality of drinking water has a critical impact on human health, several studies have been conducted to assess the quality of drinking water supplies in different parts of the world (Yassin et al. 2006; Liguori et al. 2010; Ashbolt 2015). However, despite the prevalence of waterborne diseases in Pakistan, the microbiological quality of drinking water is not closely monitored in both urban and rural areas of the country (Nabeela et al. 2014).

Karachi, the most populous city of Pakistan with a population of 16 million and an annual growth rate of 6%, is an industrial and commercial hub of the country (Government of Pakistan 2017). The main sources of drinking water supply in the city are municipal tap water and local ground (borehole) water (Alamgir et al. 2015). However, the city is facing the problem of unsafe water because of various factors which include but are not limited to water scarcity, rapid urbanization, industrialization and poor sanitary infrastructure of the city (Alamgir et al. 2015; Saleem et al. 2018). A recent study reported Karachi as one of the most highly vulnerable megacities of the world with regard to water supply and security (Keys et al. 2018). Current problems of rapid expansion and environmental pollution make it a highly significant area to be monitored for water quality (Qureshi 2010). The assessment of the microbial quality of drinking water sources of Karachi is necessary to ensure the quality of drinking water in the city.

OBJECTIVES

  • 1.

    This study aimed to determine the microbiological quality of tap and ground (borehole) water used in different administrative districts of Karachi for drinking purposes.

  • 2.

    The study also assessed the prevalence of waterborne diseases, water consumption patterns and hygiene behavior of the city residents.

MATERIAL AND METHODS

The study aimed to assess the bacteriological quality of drinking water and its potential health effects on the residents of different districts of Karachi city. Data for both parts of the current study (i.e. bacteriological analysis of water samples and community survey for assessing the public health) were collected from various localities of five administrative districts of Karachi (i.e. Malir, East, West, Central and South) as shown in Figure 1.

Figure 1

Location of collected samples sites in Karachi city, Pakistan.

Figure 1

Location of collected samples sites in Karachi city, Pakistan.

Water sample collection and bacteriological analysis

A total of 50 water samples (n = 25 tap water coming from municipal water supply and n = 25 ground water samples) were collected according to the standard protocol for the microbial examination of water (Liguori et al. 2010). Prior to sample collection, the sampling site (taps) was cleaned with alcohol swabs and 500 ml of sample was collected in commercial sterile containers. Samples were kept and transported in ice boxes within 3 h of sampling to the water testing laboratory of the DOW University of Health Sciences, where they were stored at 4 °C and were analyzed maximally within 72 h of receipt at the laboratory.

For microbiological analysis, total viable plate count (TVPC) was enumerated for all collected water samples using the standard pour plate technique. Briefly, 1 ml of water sample was mixed with nutrient agar and incubated at 37 °C for 24 h. After incubation, all colonies were counted as colony forming unit per ml (CFU/ml) of the water sample.

Total coliforms, fecal coliform (Escherichia coli), fecal enterococci, fecal streptococci and Pseudomonas were enumerated using the membrane filtration method as described previously (Khatoon & Pirzada 2010; Liguori et al. 2010). Briefly, water samples (100 ml) were passed through a 0.45 μm filter using a vacuum pump. After filtration, filter paper was placed on petri dishes containing selective nutrient mediums such as MacConkey agar, Slanetz–Bartley agar, Cetrimide-Nalidixic agar and Thiosulfate Citrate Bile Salts Sucrose agar, and incubated at various conditions to isolate coliforms and fecal coliform, fecal Enterococci, Pseudomonas and Vibrio, respectively. Isolated bacterial colonies were identified based on their characteristic macro- and microscopic features and biochemical properties.

Household-based survey

A survey-based study was conducted (n=744) to collect the health-related information of the residents of all five city districts during the period from March to September 2014. Sample size was calculated through the reported prevalence of waterborne diseases (85%) in Pakistan (Qureshi et al. 2011) with the confidence interval of 99.99%.

Information was collected through a survey questionnaire, which was designed through literature search and included questions from previous studies (Yassin et al. 2006). Survey includes questions related to the socio-demographic status, water supply sources, situation of the sanitation and cleanliness in the study area, and water-related knowledge and hygiene behavior of the participants. The survey was administered using convenience sampling by trained volunteers who visited different households and interviewed the participants who were above 18 years of age. Informed consent was taken from all the participants. All study procedures were carried out in accordance with the ‘ethical principles for medical research involving human subjects’ of the Declaration of Helsinki.

RESULTS AND DISCUSSION

Results

Microbiological analysis

Microbial analyses of tap and ground water samples are shown in Tables 1 and 2, respectively. Microbiological quality was unacceptable in all tap water and in 92% (n = 23) of the ground water samples collected from different areas of the city. The samples did not comply with the standard guidelines of drinking water set by national and international bodies. In tap and ground water samples, TVPC at 37 °C ranges from 35 to 250 CFU/ml and 0 to 150 CFU/ml, whereas total coliforms ranges from 0 to 150 CFU/100 ml and 0 to 200 CFU/100 ml, respectively.

Table 1

Microbiological quality of drinking tap water (n = 25)

District Area Total coliform (CFU/100 ml) E. coli (CFU/100 ml) Fecal Enterococci (CFU/100 ml) Streptococci (CFU/100 ml) Klebsiella spp. (CFU/100 ml) Pseudomonas spp. (CFU/100 ml) Total viable plate count (CFU/ml) 
Malir Malir >100 15 10 Nil >80 >200 >200 
Malir PakTown >80 30 15 Present >50 >200 >250 
Malir Quaidabad Nil Nil Nil >200a >200 
Malir Steel Mill 65 Nil Nil Nil 65 >200 >80 
Malir Zafar Town 60 10 20 Nil 50 >200 >200 
Central Buffer Zone >150 Nil Nil Nil >150 >200a >200 
Central North Karachi 50 Nil Nil Nil 50 >200 >200 
Central New Karachi >80 20 Nil Nil >60 >200 50 
Central Nazimabad >100 Nil Nil Nil >100 >200 >200 
Central F.B. Area 45 20 Nil Nil 25 >200 >200 
South Saddar 10 Nil Nil Nil 10 >200 25 
South Jamshed Town >60 Nil Nil Nil >60 >200 >100 
South Lyari Town 40 Nil Nil Nil 40 >200 50 
South Garden >100 Nil Nil Nil >100 >200a >200 
South Awari Tower 20 16 Nil >200 >200 
West Orangi Town 70 Nil Nil Nil 70 >200 >150 
West Baldia Town-1 >150 Nil Nil Nil >150 >200 >200 
West Baldia Town-2 42 Nil Nil Nil 42 >200 >200 
West Golimar Nil Nil Nil Nil Nil >200 >200 
West Banaras Town 77 17 Nil Nil 60 >200 >200 
East Drigh Road 68 Nil Nil Nil 68 >200 >200 
East Gulshan-e-Iqbal, Block 6 51 15 Nil 46 >200 35 
East Safoora Goth 55 Nil Nil Nil 55 >200a >150 
East PECHS 15 Nil Nil Nil 15 >200a >100 
East Gulistan-e-Johar 17 Nil Nil Nil 17 >200 35 
District Area Total coliform (CFU/100 ml) E. coli (CFU/100 ml) Fecal Enterococci (CFU/100 ml) Streptococci (CFU/100 ml) Klebsiella spp. (CFU/100 ml) Pseudomonas spp. (CFU/100 ml) Total viable plate count (CFU/ml) 
Malir Malir >100 15 10 Nil >80 >200 >200 
Malir PakTown >80 30 15 Present >50 >200 >250 
Malir Quaidabad Nil Nil Nil >200a >200 
Malir Steel Mill 65 Nil Nil Nil 65 >200 >80 
Malir Zafar Town 60 10 20 Nil 50 >200 >200 
Central Buffer Zone >150 Nil Nil Nil >150 >200a >200 
Central North Karachi 50 Nil Nil Nil 50 >200 >200 
Central New Karachi >80 20 Nil Nil >60 >200 50 
Central Nazimabad >100 Nil Nil Nil >100 >200 >200 
Central F.B. Area 45 20 Nil Nil 25 >200 >200 
South Saddar 10 Nil Nil Nil 10 >200 25 
South Jamshed Town >60 Nil Nil Nil >60 >200 >100 
South Lyari Town 40 Nil Nil Nil 40 >200 50 
South Garden >100 Nil Nil Nil >100 >200a >200 
South Awari Tower 20 16 Nil >200 >200 
West Orangi Town 70 Nil Nil Nil 70 >200 >150 
West Baldia Town-1 >150 Nil Nil Nil >150 >200 >200 
West Baldia Town-2 42 Nil Nil Nil 42 >200 >200 
West Golimar Nil Nil Nil Nil Nil >200 >200 
West Banaras Town 77 17 Nil Nil 60 >200 >200 
East Drigh Road 68 Nil Nil Nil 68 >200 >200 
East Gulshan-e-Iqbal, Block 6 51 15 Nil 46 >200 35 
East Safoora Goth 55 Nil Nil Nil 55 >200a >150 
East PECHS 15 Nil Nil Nil 15 >200a >100 
East Gulistan-e-Johar 17 Nil Nil Nil 17 >200 35 

aPseudomonas aeruginosa.

Table 2

Microbiological quality of ground water (n = 25)

District Area Bore hole depth (ft) Total coliform (CFU/100 ml) E. coli (CFU/100 ml) Fecal Enterococci (CFU/100 ml) Klebsiella spp. (CFU/100 ml) Pseudomonas spp. (CFU/100 ml) Total viable plate count (CFU/ml) 
Malir Malir-1 120 10 Nil Nil 10 >200 >150 
Malir Malir-2 100 Nil Nil Nil Nil >200 >70 
Central Gulbhar Town 200 Nil Nil Nil Nil >200 >200 
Central Ayesha Manzil 80 Nil Nil Nil Nil Nil 
Central North Karachi 11 B 120 Nil Nil Nil Nil >200 >150 
Central Dastagir 200 32 Nil Nil 32 >200 >150 
Central F.B. Area-1 150 Nil Nil Nil Nil >200 >150 
Central North Nazimabad-1 110 Nil Nil Nil Nil >200 >150 
Central F.B. Area-2 154 Nil Nil Nil >100 >07 
Central North Nazimabad-2 250 Nil Nil Nil Nil >200 200 
Central Liaquatabad 150 Nil Nil Nil Nil >200 >200 
South Near Civil Hospital 60 Nil Nil >200 >200 
South Saddar 80 >200 >100 >100 >100 >200 >200 
West HawksBay 120 Nil Nil Nil Nil Nil 
West Orangi Town-1 130 Nil Nil Nil Nil Nil >150 
West Orangi Town-2 240 20 Nil Nil 20 >200a >200 
West Baldia Town 35 >200 >50 >100 >200 >200 >200 
East Gulistan-e-Johar 110 >100 Nil Nil >100 >200 >200 
East Korangi Industrial area 200 Nil Nil Nil Nil >200 >200 
East Gulshan-e-jamal-1 80 17 Nil Nil 17 >200 >150 
East Askari 4 70 30 Nil Nil 30 >200 >150 
East Gulshan Block 13 120 Nil Nil Nil Nil >100 >200 
East Gulshan-e-Iqbal 110 Nil Nil Nil Nil >150 >200 
East PIB Colony 110 Nil Nil Nil Nil >100 >200 
East Gulshan-e-jamal-2 110 Nil Nil Nil Nil >18 >50 
District Area Bore hole depth (ft) Total coliform (CFU/100 ml) E. coli (CFU/100 ml) Fecal Enterococci (CFU/100 ml) Klebsiella spp. (CFU/100 ml) Pseudomonas spp. (CFU/100 ml) Total viable plate count (CFU/ml) 
Malir Malir-1 120 10 Nil Nil 10 >200 >150 
Malir Malir-2 100 Nil Nil Nil Nil >200 >70 
Central Gulbhar Town 200 Nil Nil Nil Nil >200 >200 
Central Ayesha Manzil 80 Nil Nil Nil Nil Nil 
Central North Karachi 11 B 120 Nil Nil Nil Nil >200 >150 
Central Dastagir 200 32 Nil Nil 32 >200 >150 
Central F.B. Area-1 150 Nil Nil Nil Nil >200 >150 
Central North Nazimabad-1 110 Nil Nil Nil Nil >200 >150 
Central F.B. Area-2 154 Nil Nil Nil >100 >07 
Central North Nazimabad-2 250 Nil Nil Nil Nil >200 200 
Central Liaquatabad 150 Nil Nil Nil Nil >200 >200 
South Near Civil Hospital 60 Nil Nil >200 >200 
South Saddar 80 >200 >100 >100 >100 >200 >200 
West HawksBay 120 Nil Nil Nil Nil Nil 
West Orangi Town-1 130 Nil Nil Nil Nil Nil >150 
West Orangi Town-2 240 20 Nil Nil 20 >200a >200 
West Baldia Town 35 >200 >50 >100 >200 >200 >200 
East Gulistan-e-Johar 110 >100 Nil Nil >100 >200 >200 
East Korangi Industrial area 200 Nil Nil Nil Nil >200 >200 
East Gulshan-e-jamal-1 80 17 Nil Nil 17 >200 >150 
East Askari 4 70 30 Nil Nil 30 >200 >150 
East Gulshan Block 13 120 Nil Nil Nil Nil >100 >200 
East Gulshan-e-Iqbal 110 Nil Nil Nil Nil >150 >200 
East PIB Colony 110 Nil Nil Nil Nil >100 >200 
East Gulshan-e-jamal-2 110 Nil Nil Nil Nil >18 >50 

aPseudomonas aeruginosa.

All tap water samples (n = 25) were contaminated with Pseudomonas spp., whereas none of the sample was found positive for Vibrio spp. Klebsiella spp. were positive in 96% (n = 24), E. coli in 32% (n = 8), fecal Enterococci spp. in 20% (n = 5) and Streptococci spp. in 4% (n = 1) of collected tap water samples.

Similarly, ground water samples were predominantly contaminated with Pseudomonas spp. (88%, n = 22), total coliforms were detected in 40% samples (n = 10), E. coli was positive in 8% (n = 2), fecal Enterococci in 8% (n = 2) and Klebsiella in 36% (n = 9). The depth of borehole water wells ranges from 35 to 250 feet, and no association was found between the degree of microbial load and depth of the wells.

Household-based community survey

A total of 744 city residents were interviewed from the five districts, among which 362 (48.6%) were females and 382 (51.3%) were males. The average age of the participants was 29.1 ± 11.2 years. Most of the participants (50.5%) were employed and the majority (71.2%) were perceived to have healthy body weight as shown in Table 3.

The responses of the participants on various aspects of water consumption, sanitation and water-related diseases are summarized in Table 4. When asked questions related to the supply and accessibility of drinking water, 83.8% of the respondents reported having access to the drinking water at their homes through municipal supply. The majority of the respondents treat water before consumption and the most preferred treatment option was boiling (60.3%). Most of the study subjects (88.1%) have access to a closed sewer toilet facility. However, around 6.2% of the interviewees defecated in open environment, mostly from the District Malir. Around 63.0% of the study subjects found their nearby localities clean.

Table 3

Demographic characteristics of study participants (n = 744)

Demographic variables n (%) 
Sex 
 Male 382 (51.3) 
 Female 362 (48.6) 
Age of participants (years) 
 18–20 169 (22.7) 
 21–30 338 (45.4) 
 31–40 111 (14.9) 
 41–50 76 (5.6) 
 51–60 23 (3.1) 
  >61 15 (2.0) 
Employment status 
 Retired 7 (0.9) 
 Employee 376 (50.5) 
 Housewife 80 (10.7) 
 Student 262 (35.2) 
Perceived body weight 
 Normal 514 (71.2) 
 Underweight 129 (17.9) 
 Overweight 79 (10.9) 
Demographic variables n (%) 
Sex 
 Male 382 (51.3) 
 Female 362 (48.6) 
Age of participants (years) 
 18–20 169 (22.7) 
 21–30 338 (45.4) 
 31–40 111 (14.9) 
 41–50 76 (5.6) 
 51–60 23 (3.1) 
  >61 15 (2.0) 
Employment status 
 Retired 7 (0.9) 
 Employee 376 (50.5) 
 Housewife 80 (10.7) 
 Student 262 (35.2) 
Perceived body weight 
 Normal 514 (71.2) 
 Underweight 129 (17.9) 
 Overweight 79 (10.9) 
Table 4

Response of participants on various aspects of water utilization and hygiene (n = 727)

Variables Frequency (N
Water supply and utilization 
 Location of drinking water source (n = 724) 
  Own home 607 83.8 
  Nearby place 117 16.2 
 Water treatment (n = 723) 
  Boiling 436 60.3 
  Adding alum 44 6.1 
  Use of filter 77 10.7 
  Bottled water 94 13.0 
  Any other 15 2.1 
  None 57 7.9 
Housing condition 
 Toilet facility (n = 723) 
  Closed sewer 637 88.1 
  Conservancy 41 5.7 
  Open field 45 6.2 
 Condition of cleanliness (n = 616) 
  Waste dumped nearby 173 28.1 
  Uncovered drain 55 8.9 
  Clean 388 63.0 
Waterborne diseases and health-seeking behavior 
 Kind of illness (n = 716) 
  Diarrhea and vomiting 272 38.0 
  Prolonged fever 68 9.5 
  Jaundice 14 2.0 
  Eye problem 55 7.7 
  Skin problem 84 11.7 
  Malaria 77 10.8 
  Typhoid 0.0 
  None 146 20.4 
 Treatment preference (n = 727) 
  Self 140 19.3 
  Local doctor 339 46.6 
  Local hospital 179 24.6 
  Hakims 16 2.2 
  Homeopath 32 4.4 
  Spiritual healer 1.0 
  Any other 14 1.9 
 Season of disease (n = 724) 
  Rainy 117 16.2 
  Summer 290 40.1 
  Winter 270 37.3 
  Spring 19 2.6 
  Autumn 14 1.9 
  None 14 1.9 
Food consumption habits and hygiene practices 
 Daily food at (n = 723) 
  Home 614 84.9 
  Outdoors 76 10.5 
  Other 33 4.6 
 Hand wash after toilet (n = 724) 
  Yes 721 99.6 
  No 0.4 
 Washing hands before taking food (n = 724) 
  Yes 712 98.3 
  No 12 1.7 
 Cover food/water (n = 724) 
  Yes 710 98.1 
  No 14 1.9 
Variables Frequency (N
Water supply and utilization 
 Location of drinking water source (n = 724) 
  Own home 607 83.8 
  Nearby place 117 16.2 
 Water treatment (n = 723) 
  Boiling 436 60.3 
  Adding alum 44 6.1 
  Use of filter 77 10.7 
  Bottled water 94 13.0 
  Any other 15 2.1 
  None 57 7.9 
Housing condition 
 Toilet facility (n = 723) 
  Closed sewer 637 88.1 
  Conservancy 41 5.7 
  Open field 45 6.2 
 Condition of cleanliness (n = 616) 
  Waste dumped nearby 173 28.1 
  Uncovered drain 55 8.9 
  Clean 388 63.0 
Waterborne diseases and health-seeking behavior 
 Kind of illness (n = 716) 
  Diarrhea and vomiting 272 38.0 
  Prolonged fever 68 9.5 
  Jaundice 14 2.0 
  Eye problem 55 7.7 
  Skin problem 84 11.7 
  Malaria 77 10.8 
  Typhoid 0.0 
  None 146 20.4 
 Treatment preference (n = 727) 
  Self 140 19.3 
  Local doctor 339 46.6 
  Local hospital 179 24.6 
  Hakims 16 2.2 
  Homeopath 32 4.4 
  Spiritual healer 1.0 
  Any other 14 1.9 
 Season of disease (n = 724) 
  Rainy 117 16.2 
  Summer 290 40.1 
  Winter 270 37.3 
  Spring 19 2.6 
  Autumn 14 1.9 
  None 14 1.9 
Food consumption habits and hygiene practices 
 Daily food at (n = 723) 
  Home 614 84.9 
  Outdoors 76 10.5 
  Other 33 4.6 
 Hand wash after toilet (n = 724) 
  Yes 721 99.6 
  No 0.4 
 Washing hands before taking food (n = 724) 
  Yes 712 98.3 
  No 12 1.7 
 Cover food/water (n = 724) 
  Yes 710 98.1 
  No 14 1.9 

When asked about their food consumption habits, 84.9% of participants showed a preference for the food prepared at home followed by 10.5% who bought outdoor food items for their daily meals. The majority of them followed the hygiene behavior and washed hands before eating (98.3%) and after using the toilets (99.6%).

When asked about waterborne diseases, the majority claimed to suffer from various waterborne diseases. Most commonly reported waterborne diseases include diarrhea and vomiting (38.0%), skin problems (11.7%) and malaria (10.8%). Additionally, other medical conditions including prolonged fever (9.5%), eye problems (7.7%) and jaundice (2.0%) were also reported. When asked about the pattern of waterborne diseases during different seasons, most repeatedly got ill in the summer and winter seasons with the frequency of 40.1% and 37.3%, respectively, while 1.9% remained healthy in all seasons.

Healthcare-seeking attitude and preferences of the study population were also recorded. The majority of the subjects received treatment at a local doctor's consultancy (46.6%), followed by treatment at a local hospital (24.6%), while 19.3% of the studied subjects practiced self-medication.

Discussion

The study sought to determine the microbial quality of two main drinking water sources (i.e. tap and ground water) in the geographic area of Karachi, Pakistan. In this investigation, microbiological quality of surface and ground water samples collected from all five districts of Karachi showed that >95% of the analyzed water samples contained bacteriological contamination. The tap water and 92% of the ground water did not comply with bacteriological standards as the TVPC at 37 °C exceeded >200 CFU/ml, with a significant detection of fecal coliforms, Enterococci and Pseudomonas spp. According to the recommendations of the World Health Organization (WHO), potable water should not have a heterotrophic bacterial count of >20 CFU/ml (WHO 2011). Moreover, drinking water should be completely free from coliform bacteria, fecal coliforms, E. coli, Enterococci and Pseudomonas aeruginosa in order to qualify as safe for consumption (Government of Pakistan 2008; WHO 2011). The presence of fecal coliforms suggests the potential presence of various enteric pathogens such as Salmonella spp., Shigella spp. and Vibrio cholera in the available water sources (Rochelle-Newall et al. 2015). Pseudomonas aeruginosa is an opportunistic pathogen and its presence in drinking water samples posed a great risk to the consumers' health (da Silva et al. 2008; Khatoon & Pirzada 2010). The presence of these indicator organisms in the collected samples indicates the contamination of sewage water with the drinking water network of the city and highlights the unsuitability of drinking water. Old sanitary infrastructure of the city could be the main source of fecal contamination in its drinking water supply network, and this may result in several self-reported serious waterborne diseases throughout the city. These results therefore indicate the need for strict surveillance and action by the relevant higher authorities to monitor and improve the drinking water supply and sanitation conditions of the city.

The results are in line with previous studies that reported a high level of microbial contamination in samples collected from different parts of the city (Alamgir et al. 2015; Saleem et al. 2018; Shakoor et al. 2018).

The majority of the study participants practiced numerous household water treatment procedures to prevent the risk of waterborne diseases. According to the community preferences, boiling of water was one of the most practiced methods for killing the waterborne pathogens. In this regard, educational and awareness programs are needed. These programs should be conducted at different community levels to promote the best water boiling practices and their effectiveness in the improvement of microbiological quality of water and ultimately the health benefits to the residents.

Although 96.43% of the study population gave a positive response when asked about washing raw food, surface washing is not enough to remove the toxic chemicals and pathogenic microorganisms which can be entered and accumulated in the vegetables during their cropping. Public awareness campaigns and strict control measures should be taken by the local and national authorities to restrict farmers' use of toxic and contaminated wastewater from sewage lines for irrigation. These measures would help in improving the quality of food as well as in preventing food- and water-related diseases.

According to the collected survey information, some of the study subjects (around 6.2%) did not have access to the closed toilet facility and they used open fields for lavatory purposes. Defecation in open areas and near water sources can also be a leading cause of the presence of fecal coliforms in drinking and domestic water. Furthermore, solid waste management is also becoming the critical public health and environmental concern for the city, which needs immediate action from both the city residents and stakeholders in the community to keep their surroundings clean and free of diseases.

The results of the study with reference to the prevalence of different waterborne diseases are in line with the previous studies conducted in different cities of Pakistan (Jabeen et al. 2011; Mahmood et al. 2011; Nabeela et al. 2014). Survey results have showed that a very large proportion of the studied population was suffering from different waterborne diseases such as diarrhea and vomiting, skin problems, malaria, prolonged fever, eye problems and jaundice. The consumption of fecal contaminated water seems to be the main cause of the spread of these illnesses.

Data are available from different parts of the world that show a significant seasonal fluctuation in the presentation of enteric diseases (Colwell 1996; Lipp et al. 2002). Seasonal variations have the potential to influence the pathogens either directly through manipulating their survival, reproduction and life cycle or indirectly by affecting their habitat, transmission and environment (Patz et al. 2005). Karachi, being the coastal city, has a moderate climate and has two main seasons: summer (longest with high humidity) and winter, while spring and autumn are comparatively shorter. The reported high prevalence of waterborne diseases in Karachi can also be because of the hot, humid conditions of the city which provide an optimal temperature for the growth and the survival of pathogens. Heavy rainfall followed by flooding in the upper areas of Pakistan also contributed to the flow and transmission of contaminated water to the main water reservoirs of Karachi (Hashmi et al. 2012). Limited data are available from Karachi about the seasonal variation and the timings and types of waterborne diseases. There is a dire need to fill this gap to design the strategies to prevent the climatic influences on disease trends.

The major reason for ground and fresh water supply contamination is poor management of wastewater and largely lacking wastewater treatment (both domestic and industrial). The contamination of metropolitan water supply in the city is caused by the entrance of sewerage water into water supply lines due to leakage of sewerage lines. Due to older infrastructure, many of the sewerage and water supply lines in the city leak. The leaking wastewater from sewerage lines also contaminates the ground water (Rahman et al. 1997).

The solid waste generated by the city has been poorly managed. About 12,000 tons per day solid waste is generated by the city, approximately 60% of which is dumped into 10 different landfill sites around the city while the rest stays on the street (Rahman 2013; Abbasi et al. 2015; Sabir et al. 2016). Leachate and surface water run-off from landfill sites have been reported to contaminate the ground water and fresh water sources chemically and biologically where controlling arrangements were not made, and this could lead to serious health issues in consumers.

CONCLUSION

In conclusion, a significant proportion (96%) of the collected samples did not comply with the standard guidelines which raise concern about the microbiological quality of drinking water available from different sources and highlight the importance of strict monitoring and control systems. Although E. coli and fecal Enterococci were absolutely absent in the majority of the tested samples (Tables 1 and 2), further preventive actions need to be taken seriously to improve the quality of drinking water since the total viable count in all of the tested samples is far greater than the permissible range set according to the national and international criteria. Total counts of microorganisms reflect the sanitary quality of water (Mihdhdir 2009). Rapid urbanization, unplanned city constructions, old networks of asbestos cement pipes that have completed their life span and now have breakages and leaks are some of the major causes of inadequate water sanitation in the city. Moreover, despite the good hygiene practices of studied subjects, a large proportion of the participants had caught characteristic waterborne infections.

RECOMMENDATIONS

Based on study results, immediate actions are recommended to ensure the supply of potable drinking water to the city residents. Our study did not examine the physical and chemical quality of drinking water, and further studies are needed to assess both the physico-chemical and microbiological quality of the city's drinking water supply and their impact on human health.

COMPETING INTERESTS

The authors report that there are no conflicts of interest.

ACKNOWLEDGEMENTS

The authors would like to acknowledge the DOW University of Health Sciences for providing financial support to this project. The authors are grateful to Prof. Dr Syed Khaqan Hasan and Mr Munawar Qureshi for all the support and assistance to conduct this study.

REFERENCES

REFERENCES
Abbasi
H. N.
,
Lu
X.
&
Zhao
G.
2015
An overview of Karachi solid waste disposal sites and environs
.
Journal of Scientific Research and Reports.
6
(
4
),
294
303
.
Alamgir
A.
,
Khan
M. A.
,
Hany
O. E.
,
Shaukat
S.
,
Mehmood
K.
,
Ahmed
A.
,
Ali
S.
,
Riaz
K.
,
Abidi
H.
,
Ahmed
S.
&
Ghori
M.
2015
Public health quality of drinking water supply in Orangi town, Karachi, Pakistan
.
Bulletin of Environment, Pharmacology and Life Sciences.
4
,
88
94
.
Bain
R.
,
Cronk
R.
,
Wright
J.
,
Yang
H.
,
Slaymaker
T.
&
Bartram
J.
2014
Fecal contamination of drinking-water in low-and middle-income countries: a systematic review and meta-analysis
.
PLoS Medicine
11
(
5
),
e1001644
.
da Silva
M. E.
,
Santana
R. G.
,
Guilhermetti
M.
,
Camargo Filho
I.
,
Endo
E. H.
,
Ueda-Nakamura
T.
,
Nakamura
C. V.
&
Dias Filho
B. P.
2008
Comparison of the bacteriological quality of tap water and bottled mineral water
.
International Journal of Hygiene and Environmental Health
211
(
5–6
),
504
509
.
Daud
M. K.
,
Nafees
M.
,
Ali
S.
,
Rizwan
M.
,
Bajwa
R. A.
,
Shakoor
M. B.
,
Arshad
M. U.
,
Chatha
S. A.
,
Deeba
F.
,
Murad
W.
&
Malook
I.
2017
Drinking water quality status and contamination in Pakistan
.
BioMed Research International
2017
.
Government of Pakistan
2008
Pakistan Environmental Protection Agency. (Ministry of Environment)
.
National Standards for Drinking Water Quality (NSDWQ)
.
Ministry of Health, World Health Organization, UNICEF
.
Available from: http://www.environment.gov.pk/act-rules/DWQStd-MAY2007.pdf (accessed 16 February 2018)
.
Government of Pakistan
2017
Pakistan Bureau of Statistics. Province-Wise Provisional Results of Census
. .
Griggs
D.
,
Stafford-Smith
M.
,
Gaffney
O.
,
Rockström
J.
,
Öhman
M. C.
,
Shyamsundar
P.
,
Steffen
W.
,
Glaser
G.
,
Kanie
N.
&
Noble
I.
2013
Policy: sustainable development goals for people and planet
.
Nature
495
(
7441
),
305
.
Hashmi
H. N.
,
Siddiqui
Q. T.
,
Ghumman
A. R.
&
Kamal
M. A.
2012
A critical analysis of 2010 floods in Pakistan
.
African Journal of Agricultural Research
7
(
7
),
1054
1067
.
Jabeen
S.
,
Mahmood
Q.
,
Tariq
S.
,
Nawab
B.
&
Elahi
N.
2011
Health impact caused by poor water and sanitation in district Abbottabad
.
Journal of Ayub Medical College Abbottabad
23
(
1
),
47
50
.
Keys
P. W.
,
Wang-Erlandsson
L.
&
Gordon
L. J.
2018
Megacity precipitation sheds reveal tele-connected water security challenges
.
PLoS ONE
13
(
3
),
e0194311
.
Khatoon
A. M.
&
Pirzada
Z. A.
2010
Bacteriological quality of bottled water brands in Karachi, Pakistan
.
Biologia (Bratisl)
56
,
137
143
.
Liguori
G.
,
Cavallotti
I.
,
Arnese
A.
,
Amiranda
C.
,
Anastasi
D.
&
Angelillo
I. F.
2010
Microbiological quality of drinking water from dispensers in Italy
.
BMC Microbiology
10
(
1
),
19
.
Lipp
E. K.
,
Huq
A.
&
Colwell
R. R.
2002
Effects of global climate on infectious disease: the cholera model
.
Clinical Microbiology Reviews
15
(
4
),
757
770
.
Mahmood
A.
,
Muqbool
W.
,
Mumtaz
M. W.
&
Ahmad
F.
2011
Application of multivariate statistical techniques for the characterization of ground water quality of Lahore, Gujranwala and Sialkot (Pakistan)
.
Pakistan Journal of Analytical & Environmental Chemistry
12
(
1 & 2
),
11
.
Memon
M.
,
Soomro
M. S.
,
Akhtar
M. S.
&
Memon
K. S.
2011
Drinking water quality assessment in Southern Sindh (Pakistan)
.
Environmental Monitoring and Assessment
177
(
1–4
),
39
50
.
Nabeela
F.
,
Azizullah
A.
,
Bibi
R.
,
Uzma
S.
,
Murad
W.
,
Shakir
S. K.
,
Ullah
W.
,
Qasim
M.
&
Häder
D. P.
2014
Microbial contamination of drinking water in Pakistan – a review
.
Environmental Science and Pollution Research
21
(
24
),
13929
13942
.
Patz
J. A.
,
Campbell-Lendrum
D.
,
Holloway
T.
&
Foley
J. A.
2005
Impact of regional climate change on human health
.
Nature
438
(
7066
),
310
.
Qureshi
S.
2010
The fast growing megacity Karachi as a frontier of environmental challenges: urbanization and contemporary urbanism issues
.
Journal of Geography and Regional Planning
3
(
11
),
306
321
.
Qureshi
E. M.
,
Khan
A. U.
&
Vehra
S.
2011
An investigation into the prevalence of water borne diseases in relation to microbial estimation of potable water in the community residing near River Ravi, Lahore, Pakistan
.
African Journal of Environmental Science and Technology
5
(
8
),
595
607
.
Rahman
M. A.
2013
Revisiting solid waste management (SWM): a case study of Pakistan
.
International Journal of Scientific Footprints
1
(
1
),
33
42
.
Rahman
A.
,
Lee
H. K.
&
Khan
M. A.
1997
Domestic water contamination in rapidly growing megacities of Asia: case of Karachi, Pakistan
.
Environmental Monitoring and Assessment
44
(
1–3
),
339
360
.
Rahman
A. E.
,
Moinuddin
M.
,
Molla
M.
,
Worku
A.
,
Hurt
L.
,
Kirkwood
B.
,
Mohan
S. B.
,
Mazumder
S.
,
Bhutta
Z.
,
Raza
F.
&
Mrema
S.
2014
Childhood diarrhoeal deaths in seven low-and middle-income countries
.
Bulletin of the World Health Organization
92
,
664
671
.
Rochelle-Newall
E.
,
Nguyen
T. M.
,
Le
T. P.
,
Sengtaheuanghoung
O.
&
Ribolzi
O.
2015
A short review of fecal indicator bacteria in tropical aquatic ecosystems: knowledge gaps and future directions
.
Frontiers in Microbiology
6
,
308
.
Sabir
W.
,
Waheed
S. N.
,
Afzal
A.
,
Umer
S. M.
&
Rehman
S.
2016
A study of solid waste management in Karachi city
.
Journal of Education & Social Sciences
4
(
2
),
151
163
.
Saleem
F.
,
Mustafa
A.
,
Kori
J. A.
,
Hussain
M. S.
&
Kamran Azim
M.
2018
Metagenomic characterization of bacterial communities in drinking water supply system of a Mega city
.
Microbial Ecology
76
,
899
910
.
Van Leeuwen
F. X.
2000
Safe drinking water: the toxicologist's approach
.
Food and Chemical Toxicology
38
,
S51
S58
.
WaterAid
2018
The Water Gap – The State of the World's Water
.
WHO
2011
Guidelines for Drinking-Water Quality
.
World Health Organization
,
Geneva
.

Author notes

These authors contributed equally to this work.