Assessment of Bacteriological Quality of Drinking Water in some Household Water Filter Systems in Benghazi City

Water is very important to human beings. Although human life can exist for many days without food, the absence of water for only a few days has fatal consequences. A wide variety of commercial water treatment systems are available for application to treat very small quantities, such as for individual homes or taps. These can treat virtually any water quality problem. It is important to have a good understanding of the specific water quality problems before selecting water treatment system. It is also important that products be tested and approved by a qualified independent certification organization to have confidence that the device will indeed perform as the vendor claims. The present study aimed to assess the bacteriological quality of drinking water in some household water filter systems in Benghazi city. The study was carried out on a total of 600 water samples (300 tap water samples and 300 filter water devices samples). All water samples were examined for enumeration of viable heterotrophic bacteria by pour plate method and enumeration of total coliforms (TC) by both the multiple tube fermentation (MTF) and membrane filtration (MF) methods and for thermotolerant coliforms (TTC), Fecal streptococci (FS), and Pseudomonas aeruginosa (P. aeruginosa) by the MF method. According to Libyan guidelines, out of 600 examined drinking water samples 76.8% were acceptable. The highest percentage of acceptable samples was revealed from reverse osmosis (RO) system (90.7%), followed by charcoal filter (83.3%), tap water distribution system (DS) (82.3%), and only 54.7% from tap water tanks. It was concluded from this study that filtered water samples were found to be superior to tap water samples as regards their bacteriological aspects. In addition, P. aeruginosa was considered as an excellent indicator for the efficiency of the water filters. INTRODUCTION: The key to increase human productivity and long life is good quality water.(1) Drinking water is an important resource all around the globe. (2) It is one of the most important commodities which man has exploited than any other resource for sustenance of his life. (3) Outbreaks of waterborne infectious diseases via the use of contaminated drinking water still pose a serious health threat worldwide, despite the fact that drinking water is one of the most closely 735 Bull High Inst Public Health Vol.38 No.4 [2008] monitored and strictly regulated resources. Careful estimates indicate that each year about 350 million people are infected by waterborne pathogens, with 10 to 20 million succumbing due to severe cases of infection.(4) This phenomenon is far from being restricted to developing countries but also threatens developed countries. In the United States (US), almost 430,000 cases were reported in 126 outbreaks of waterborne infectious diseases during years from 2003 to 2005. (5) The number of different types of pathogens that can be present in water as a result of contamination with human or animal feces is very large and it is not possible to test water samples for each specific pathogen. Therefore, scientists and public health officials typically choose to monitor non pathogenic bacteria that are usually associated with pathogens transmitted by fecal contamination; but are more easily sampled and measured. These associated bacteria are called indicator organisms. (6) Aeromonas species and P. aeruginosa have been advocated as a means of monitoring the hygienic quality of drinking water. They indicate the general cleanliness of the distribution system and are used to assess the quality of filter water devices as their presence suggests non compliance with good manufacturing. (7, 8) A wide variety of commercial water treatment systems are available for application to treat very small quantities, such as for individual homes or taps. These can treat virtually any water quality problem. A major goal in water treatment is to produce clear, good tasting water. Adsorption has been used for many years to help achieve this goal by removing organics that cause taste, odor and color in drinking water. Recently it is also becoming an important method for protecting public health by removing toxic organic chemicals from drinking water. (9, 10) There are a number of methods Abaza et al., 736 available to improve or enhance drinking water quality. People work very hard to improve treatments like purification and disinfection and to get perfect product-drink safe for health and necessary for life called simply Household water filters (HHWFs).(11,12) Water filters have been introduced for many centuries; they are closely related to the history of water. Various filtration methods for reducing microbes in water have been widely known and practiced for decades. (13) According to the history of water treatment the use of water filters began more than 4000 years ago. As early as 1500 years ago, Egyptians recommended the application of coagulant alum to settle out the suspended solids from water. (14) Household water management practices have been introduced in approximately 50 developing countries. These range from simple filters made from sari cloth and nylon to commercially produced sachets of flocculantdisinfectants. (15) Geldreich et. al., (16) reported that, installation and use by the public of in-thehome, point of use (POU) water treatment devices have increased during the last several years. This trend has paralleled increased consumer awareness of the potential health risks posed by some community drinking water systems. Although filtration was recognized for removal of undesirable particles and microbes, several studies showed high bacterial counts in fresh filtered than in tap water after approximately one week of use.(17, 18, 19) For this reason, the assessment of the biological characteristics of filtered and tap water is of great significance. Aim of the Work: The present study aimed to assess the bacteriological quality of drinking water in some household water filter systems in Benghazi city. 737 Bull High Inst Public Health Vol.38 No.4 [2008] Material & Methods: The study was carried out during 11 months, from the beginning of March 2008 till the end of January 2009, on a total of 600 water samples (300 tap water samples and 300 filter water devices samples). These samples were collected monthly. Tap water samples: A total of 300 water samples were collected from 21 various areas in Benghazi city (130 samples from DS and 170 samples from tanks). Filter water devices: 1) Charcoal filter samples A total of 150 water samples were collected from 14 various areas in Benghazi city. 2) RO filter system samples A total of 150 water samples were collected from 16 various areas in Benghazi city. Water samples were aseptically collected in 500 ml sterile bottles. These bottles contained sodium thiosulphate for all water samples. The water samples were directly transferred to the laboratory and examined within 1-6 hours of collection. Each sample was vigorously shaken and subjected to bacteriological examination. 1) Enumeration of heterotrophic plate count (HPC) using standard pour plate method. It was done using the standard pour plate method. Water samples were subjected to serial 10fold dilutions using sterile peptone water, and one ml of each sample and / or the appropriate dilutions were dispensed into sterile glass Petri dishes. Duplicate petridishes for appropriate dilutions were inoculated. Then 15 ml volumes of molten sterile plate count agar (PCA) tempered approximately to 45oC was aseptically poured into each plate. The agar was thoroughly mixed with the sample aliquots by gentle to and fro, clockwise and anticlockwise movements. The agar was allowed to set and solidify. The plates were Abaza et al., 738 then inverted and incubated at 37oC for 48 hours. The plates showing 30-300 colonies were counted using Quebec colony counter and expressed as cfu /ml of the sample 2) Enumeration of TC by MTF. i. Presumptive phase Water sample volumes of 50 and 10 ml were used .The 50 ml volumes were inoculated into bottles containing 50 ml double strength lauryl tryptose broth (LTB) and the 10 ml volumes of water were inoculated into each of five replicate tubes each containing 10ml of double strength LTB. All the inoculated bottles and tubes were shaken and incubated at 37°C for 2448 hours. After 24 hours each tube and bottle was shaken gently and was examined for turbidity and/ or gas production. All bottles and tubes showing no gas or turbidity were re-incubated and re-examined at the end of 48 hours. Production of growth and or gas in tubes or bottles within 48 hours was considered a positive result for presumptive test and was subjected to: ii . Confirmed Phase: Two loopfuls from each positive presumptive tube or bottle were inoculated into tubes each containing 5 ml single strength Brilliant Green lactose bile broths (BGLBB). All tubes were shaken on a vortex mixer and incubated at 37°C for 48 hours. Tubes showing turbidity and gas production were considered positive for confirmed phase. The most probable number (MPN) of TC/100 ml of water sample was calculated from MaCradey probability tables. 3) Enumeration of TC, TTC, FS, P. aeruginosa by MF. Membrane filters Sterile cellulose acetate membrane filters of 0.45um pore size and 47mm diameter were used. Filtration unit: The used filter holding assembly consisted of three glass funnels that fasten to three receptacles bearing porous plates to support 739 Bull High Inst Public Health Vol.38 No.4 [2008] the membrane filters. The parts of assembly were sterilized by autoclaving 121° C f or 20

Bull High Inst Public Health Vol.38 No.4 [2008]   monitored and strictly regulated resources.
Careful estimates indicate that each year about 350 million people are infected by waterborne pathogens, with 10 to 20 million succumbing due to severe cases of infection. (4)This phenomenon is far from being restricted to developing countries but also threatens developed countries.In the United States (US), almost 430,000 cases were reported in 126 outbreaks of waterborne infectious diseases during years from 2003 to 2005. (5)e number of different types of pathogens that can be present in water as a result of contamination with human or animal feces is very large and it is not possible to test water samples for each specific pathogen.Therefore, scientists and public health officials typically choose to monitor non pathogenic bacteria that are usually associated with pathogens transmitted by fecal contamination; but are more easily sampled and measured.These associated bacteria are called indicator organisms. (6)romonas species and P. aeruginosa have been advocated as a means of monitoring the hygienic quality of drinking water.They indicate the general cleanliness of the distribution system and are used to assess the quality of filter water devices as their presence suggests non compliance with good manufacturing. (7,8) ide variety of commercial water treatment systems are available for application to treat very small quantities, such as for individual homes or taps.
These can treat virtually any water quality problem.A major goal in water treatment is to produce clear, good tasting water.
Adsorption has been used for many years to help achieve this goal by removing organics that cause taste, odor and color in drinking water.Recently it is also becoming an important method for protecting public health by removing toxic organic chemicals from drinking water. (9,10) re are a number of methods available to improve or enhance drinking water quality.People work very hard to improve treatments like purification and disinfection and to get perfect product-drink safe for health and necessary for life called simply Household water filters (HHWFs). (11,12)ter filters have been introduced for many centuries; they are closely related to the history of water.Various filtration methods for reducing microbes in water have been widely known and practiced for decades. (13)cording to the history of water treatment the use of water filters began more than 4000 years ago.As early as 1500 years ago, Egyptians recommended the application of coagulant alum to settle out the suspended solids from water. (14)usehold water management practices have been introduced in approximately 50 developing countries.
These range from simple filters made from sari cloth and nylon to commercially produced sachets of flocculantdisinfectants. (15) Geldreich et.al., (16) reported that, Although filtration was recognized for removal of undesirable particles and microbes, several studies showed high bacterial counts in fresh filtered than in tap water after approximately one week of use. (17,18,19) Fthis reason, the assessment of the biological characteristics of filtered and tap water is of great significance.

Aim of the Work:
The present study aimed to assess the bacteriological quality of drinking water in some household water filter systems in Benghazi city.

Material & Methods:
The study was carried out during 11 months, from the beginning of March 2008 till the end of January 2009, on a total of 600 water samples (300 tap water samples and 300 filter water devices samples).
These samples were collected monthly.

Tap water samples:
A total of 300 water samples were collected from 21 various areas in Benghazi city (130 samples from DS and 170 samples from tanks).

Filter water devices: 1) Charcoal filter samples
A total of 150 water samples were collected from 14 various areas in Benghazi city.3) Enumeration of TC, TTC, FS, P.

2) RO filter system samples
aeruginosa by MF.

Membrane filters
Sterile cellulose acetate membrane filters of 0.45um pore size and 47mm diameter were used.

Filtration unit:
The used filter holding assembly consisted of Procedures were performed according to the methods described by Eaton et al. (20) Counting: • Plates showing 20 to 80 coliform colonies not more than 200 colonies of all types per membrane were counted using Quebec colony counter.
• Both typical and atypical coliform colonies were counted.
• Typical TC colonies on m-Endo agar were pink to dark red in color with a green metallic sheen.
• Atypical coliform colonies on m-Endo agar were dark red mucoid, or nucleated colonies without metallic sheen.
• It was performed in a similar manner to that employed for enumeration of TC but by using m-FC agar plates.These plates were inverted and incubated at 35-37°C for 2 hours and then incubated at 44.5 °C for 24 hours.

3.b.Membrane Filtration Technique for FS: (20)
It was performed in a similar manner to that employed for enumeration of TC but by using m-KF agar plates.Plates were left for 30 min, then inverted and incubated at 35°C for 48 hours.

P. aeruginosa: (20)
It was performed in a similar manner to that employed for enumeration of TC but by using m-PA agar plates.Plates were left for 30 min, then were inverted and incubated at 35˚C for 48 hours.

Results:
According to WHO and Libyan guidelines, out of the 600 examined water samples 461(76.8%)were acceptable and 139(23.2%)were unacceptable.
The results of this study can be summarized as follows:

Discussion:
The present study revealed that 23.2% of the 600 examined drinking water samples were bacteriologically unsatisfactory and were considered unacceptable as they failed to meet the Libyan guidelines.Nearly a similar percentage of 20% was reported by Brownell et al., (21) in Canada.Higher percentages were reported by Copeland et al. (22) in Brazil (30.3%) ,Mahjoub et al., (23) in Libya (30.4%) , and Lamka et al. (24) in United States (35%).A much lower percentage was reported by Essa (25) in Egypt (3%).
Household water treatment is a practical strategy to prevent waterborne diseases. (26)RO system and charcoal carbon are commonly used in Libya. (27)RO system in this study showed maximum reduction of microbial contamination and provided the highest percentage of acceptable water samples (90.7%).Nearly a similar percentage was reported by Payment et al., (28) in United States (93%).
A lower percentage was reported by Miles et al., (18) in United States (73%).
The charcoal filters generally improve the quality of household drinking water by removing objectionable tastes and odors as well as dirt, rust, and sand. (29)In this study, 83.3% of the 150 examined drinking water samples after charcoal filtration were bacteriologically satisfactory and met the Libyan guidelines.Johnston and Burt (30) reported nearly similar results for activated carbon (AC) filters (80.1%).
Taylor et al (31) tested four POU carbon filter devices, installed in the cold water line, they found that these devices removed 60-80 % of the influent chlorinated organic compounds when new filter cartridges were first put on line, but after 6-8 weeks, removal was reduced to < 10 % as a result of decreased effectiveness of the filters.
Although coliform organisms may not always be directly related to the presence of fecal contamination or pathogens in drinking water, the coliform test is still useful for monitoring the microbial quality of drinking water. (32)is study revealed that TC were isolated from 18.2% of examined tank water samples, this could suggest bacterial regrowth, decrease in free chlorine during storage or old tanks.Much higher percentages were reported by Chaidez et.
TTC were considered more faecal specific than TC, and their detection was used routinely. (35)This study showed that 4.1% of the examined drinking water samples yielded TTC from tanks.A much higher percentage was reported by Chaidez et.al., (36) in United States (20%).
Bull High Inst Public Health Vol.38 No.4 [2008]   In the present study the frequency of isolation of TC and TTC from RO systems were (6.0%) and (2.0%) respectively.
Lechevallier et.al., (37) reported isolation rates of (28.7%) and (3.1%) for TC and TTC from granular activated carbon (GAC) filters respectively.This could be explained by the difficulty to maintain free residual chlorine in all parts of the filters.Some outbreaks of gastrointestinal illness have been attributed to drinking water contaminated with P. aeruginosa.
This organism is capable of growth in low substrate conditions and in the presence of high chlorine levels. (38)In the present study, P. aeruginosa was isolated from filter water devices morning samples (one sample from charcoal filter and three samples from RO filter system).This could be due to the fact that RO systems have plastic storage tanks which might help the colonization of bacteria and their resistance to disinfection: Another factor may be attributed to the membranes being unchanged as recommended by the manufacturers.Nearly a similar result was reported by Vonberg et al., (39) where only one water sample yielded P. aeruginosa after filtration.
Three different brands of household filter devices designated A, B and C were examined in this study.It was found that RO system brand A was the best brand as regards the bacteriological quality and its compliance with the Libyan standards for drinking water (98.2%).It possessed the highest efficiency in purifying water, followed by RO system brand B and C; (93.3 %) and (80.0%) respectively, this could be due to accuracy, quality and efficiency of manufacturing parts of brand A. This was the same with the studied charcoal filters.In this present study , all the 55 water samples (100%) from brand A RO filter system had HPC <1 cfu/ml.
In the present study as regards installment duration of filter devices and presence of indicator organisms in examined drinking water samples after filtration process, high percentages were recorded from filter water devices samples of installment duration above 12 months.It could be explained by the possibility that with prolonged duration the devices hypothetical durability and efficiency lessens.Another explanation may be that membranes were not changed according to country of origin or manufacturer's instructions time.Reasoner et al., (41) (42) This present study showed that out of (600) examined tap water samples, 68(88.2%)were positive for TC detection by MTF and MF methods and only 8 (11.8%) were positive by MTF method and negative by MF method.An agreement of 93 % was found between both methods in detection of TC.

Conclusions:
It can be concluded from this study that: 1. Filtered water samples were found to be superior to tap water samples as regards their bacteriological aspects.
installation and use by the public of in-thehome, point of use (POU) water treatment devices have increased during the last several years.This trend has paralleled increased consumer awareness of the potential health risks posed by some community drinking water systems.
The agar was allowed to set and solidify.The plates were then inverted and incubated at 37ºC for 48 hours.The plates showing 30-300 colonies were counted using Quebec colony counter and expressed as cfu /ml of the sample 2) Enumeration of TC by MTF.i. Presumptive phase Water sample volumes of 50 and 10 ml were used .The 50 ml volumes were inoculated into bottles containing 50 ml double strength lauryl tryptose broth (LTB) and the 10 ml volumes of water were inoculated into each of five replicate tubes each containing 10ml of double strength LTB.All the inoculated bottles and tubes were shaken and incubated at 37°C for 24-48 hours.After 24 hours each tube and bottle was shaken gently and was examined for turbidity and/ or gas production.All bottles and tubes showing no gas or turbidity were re-incubated and re-examined at the end of 48 hours.Production of growth and or gas in tubes or bottles within 48 hours was bottle were inoculated into tubes each containing 5 ml single strength Brilliant Green lactose bile broths (BGLBB).All tubes were shaken on a vortex mixer and incubated at 37°C for 48 hours.Tubes showing turbidity and gas production were considered positive for confirmed phase.The most probable number (MPN) of TC/100 ml of water sample was calculated from MaCradey probability tables.
three glass funnels that fasten to three receptacles bearing porous plates to support Bull High Inst Public Health Vol.38 No.4 [2008] the membrane filters.The parts of assembly were sterilized by autoclaving 121° C f or 20 minutes.
The TC density was calculated by the following equation.Typical colonies and any atypical colonies were verified by picking at least 5 colonies from each plate and incubating them in LTB at 35˚ C for 48 hours and then in BGLBB at 35˚ C for 48 hours.Gas formed in LTB and confirmed in BGLBB within 48 hours verified the colony as a coliform.For verified coliform counts, the initial count was adjusted based upon the positive verification percentage and was reported as "verified coliform counts/

2.
The changing of the membranes of the filter devices according to the manufacturer َs instructions resulted in raised efficiency of filter devices where no indicator organisms were isolated from RO systems with changed membranes.3. P. aeruginosa is considered as an excellent indicator for the efficiency of the water filters. of filtered water should be followed, considering the addition of P. aeruginosa as an indicator of filtered water quality.3-A further research is needed to evaluate the extent and amount of carbon penetration through charcoal filters and RO systems.

:
Frequency of isolation of the indicator organisms from the examined drinking water samples according to the duration of installing the RO filter system devices. of isolation of indicator organisms from filter water samples and changing of the filter device membranes according to the manufacturersYes*: change of membrane according to the manufacturer's instructions No**: no change of membrane