Study Notes on Water Quality and Analysis

Water Analysis and Quality Standards

Code of Sanitation and Examination of Drinking Water

  • Page Reference: P.D. 856, Sec 12, Chapter II
  • Department of Health Regulation:
      - Examination of drinking water is to be conducted exclusively in accredited private and government laboratories by the Department of Health (now referred to as the Ministry).
      - Laboratories performing water analysis must be accredited by the DOH.

Philippine National Standard for Drinking Water (PNSDW)

  • Year of Establishment: 1963
  • World Health Connection: Initially based on the World Health International Standard for Drinking Water set in 1958.
  • Revisions: Multiple revisions, with the latest being in 2017 after 2007. The revisions were necessitated by:
      1. Enforcement challenges faced by water service providers in meeting WHO standards.
      2. Introduction of new parameters for measurement.
      3. Improvement of the drinking water safety framework aligning with WHO standards set in 2011.
      4. Needs articulated in the Sustainable Development Goals (SDGs).
      5. Quality standards required during emergency situations.

Standards for Drinking Water Quality

  • Quality Measures: Drinking water quality is quantified based on microbiological, physical, chemical, and radiological constituents.
  • Classification of Parameters:
      - Mandatory Parameters: Legally required, affecting health acutely or chronically, rendering water unacceptable for drinking.
      - Primary Parameters: Side-specific parameters that could affect health upon exposure.
      - Secondary Parameters: Indirectly affect health; could make water unacceptable for drinking.
      - Emergency Parameters: Temporary measures enacted by local government units (LGUs) during emergencies.
Mandatory Parameters Include:
  1. Thermotolerant coliform/E. coli
  2. Arsenic
  3. Cadmium
  4. Lead
  5. Nitrate
  6. Color
  7. Turbidity
  8. pH
  9. Total Dissolved Solids
  10. Disinfectant residual
  • Monitoring Frequency for Mandatory Parameters:
      - Thermotolerant coliform/E. coli: monthly
      - Physical and chemical analyses: twice a year

Drinking Water Presentation

  • Drinking water must be:
      - Clear
      - Colorless
      - Free from objectionable odors and tastes.
  • Must not contain any harmful substances, organisms, chemicals, or radioactive materials.

Health Risks from Microbes in Drinking Water

  • Strategies include a Barrier Approach and establishing Allowable Limits.
      - Barrier Approach: Treatment of wastewater and raw water through disinfection, purification, hydro purification, and reverse osmosis.

Water-Borne Microbial Pathogens

Pathogen Types and Examples:
  • Bacteria: E. coli, Salmonella, Shigella, Campylobacter, V. cholerae
  • Viruses: Hepatitis A and E
  • Protozoa: E. histolytica, Giardia, Cryptosporidium
  • Helminths: Nematodes, Cestodes, Flukes
Specific Bacterial Pathogen Characteristics:
  • E. coli: Indicator of fecal pollution, survives outside the environment, sensitive to chlorine.
  • Salmonella: Causes diarrhea and typhoid fever; requires significant water volumes for isolation in detection.
  • Shigella: Causes bacillary dysentery; transmitted via contaminated food or hands.

Detection and Monitoring Techniques

Salmonella Detection Techniques:
  1. Concentration Techniques
  2. Enrichment Techniques
  3. Selective Growth
  4. Biochemical Reactions
  5. Genus Identification
Fecal Indicator Organisms Criteria:
  1. Part of the normal flora in healthy individuals.
  2. Always present when pathogens are present but absent in uncontaminated water.
  3. Present in large numbers in feces.
  4. Easily isolated and identified.
  5. Respond similarly to environmental conditions and treatment processes.
Coliform Groups Defined:
  • Represent 10% of intestinal microflora (Enterobacteriaceae).
  • Capable of fermenting lactose, producing acid and gas within 24-48 hours at 35°C.
      - Total Coliform: Includes E. coli, Enterobacter, Klebsiella, Citrobacter - should not be detected in treated water.
      - Fecal Coliform: Subset tolerating 44.5°C; indicates fecal contamination, predominantly E. coli.

Water Microbiology Testing Procedures

Multiple Tube Fermentation Test (MTFT):
  • A method to detect and estimate total coliforms.
  • Results reported as Most Probable Number (MPN), based on positive reactions from multiple tubes.
      - Presumptive Phase: Uses Lauryl Tryptose broth, incubating for 48 hours at 35°C.
      - If gas or acidic growth is detected, the tubes produce heavy growth, undergoing confirmatory testing.
Confirmatory Testing:
  • Two main phases:
      1. Culture in Brilliant Green Lactose Bile Broth (BGLB) for total coliform.
      2. Use of EC Medium for fecal coliform detection, with incubation at 44.5°C.

Reporting of Water Sample Results

  • Results are to be documented on a raw data sheet for clarity.
  • Example of Reporting:
      - Sample 1:
        - Total Coliforms: 4.6, Remark: FAILED
        - Thermotolerant Coliform: 2.6, Remark: FAILED
      - Sample 2:
        - Total Coliform Gas Production: 4.6,
        - Thermotolerant: <1.1, Remark: FAILED.

Heterotrophic Plate Count (HPC) Procedures

Sample Collection:
  1. Samples should be analyzed promptly after collection to minimize changes in bacterial populations.
  2. At least two replicate plates are prepared for each sample.
Heterotrophic Plate Count Method:
  • Estimate the number of live heterotrophic bacteria, indicating the effectiveness of water treatment.
  • Steps for HPC include:
      1. Aseptically collect samples and plate them.
      2. Use proper counting techniques based on the number of observed colonies and provide appropriate reporting for colony-forming units (CFU) per ml.
Reporting Rules:
  • When counting colonies:
      - Less than 300 colonies: Report as is.
      - More than 300 colonies: Count defined squares within plates, applying multiplication factors based on plate type (glass or plastic).
      - Reference for HPC: In drinking water, should be less than 500 CFU/ml; in dialysis water, cut-off is less than 200 CFU/ml.
Guidelines on Rounding:
  • Rounding rules apply for reporting average colony counts, e.g., rounding 156 to 160 if rounding up based on significant figures.

Conclusion

  • Assessing drinking water quality continuously is fundamental to ensure public health safety. The integrated assessment of microbiological, physical, and chemical parameters forms the basis for regulatory compliance and public health standards.

  • As water quality parameters evolve, regulatory frameworks must adapt, informed by ongoing scientific research and public health needs.