Water Quality Testing: Risks, Detection, and Prevention in Food Plants
- Joshna Bora
- 4 days ago
- 7 min read
Water quality testing is an essential process that involves evaluating water in three different aspects: physical, chemical, and biological, to make sure the water is suitable for its intended use and to detect risks related to public health. Physical water quality testing assesses the water based on sensory attributes like colour, odour, taste, and turbidity. Chemical water quality testing, which includes tests like pH, total dissolved solids (TDS), hardness, chlorine, nitrates, heavy metals, and other volatile organic compounds, determines the level of organic and inorganic matter dissolved in water. Biological water quality testing involves the monitoring of water for harmful bacteria or viruses like Salmonella, E. coli, coliforms, hepatitis A, enterovirus, legionella, etc., which can cause severe waterborne illness. There are radiological parameters as well, which screen for elements like alpha and beta emitters.
Impact of waterborne diseases
As reported by the World Health Organization (WHO), 1 million people worldwide die every year from diarrhoea; among these, 395000 are children under 5 years old. In 2025, India reported ~2,350,000 cases of ADD (Acute Diarrhoeal Disease), ~567,000 cases of typhoid fever, ~ ~40,500 cases of Hepatitis A, and around 1,131 cases of cholera. (Reference: MINISTRY OF HEALTH AND FAMILY WELFARE)
The primary culprit here is contaminated water, which causes these infections. Apart from diarrhoea, diseases like cholera, dysentery, hepatitis A, typhoid, and polio are also related to contaminated drinking water and inadequate sanitation. If we talk about specific microbes that contribute to such diseases, they include Escherichia coli (E. coli), Salmonella, Shigella, Campylobacter, hepatitis A virus, enteroviruses, Vibrio cholerae, coliforms, etc. Even in the food and beverage manufacturing industries, the finished goods are often tested; if a pathogen is detected, it leads to a costly food recall. But what can be the source of contamination? The answer is that it can be raw ingredients, the equipment in which the food items are handled, personnel, or it can even be water. Water is usually the most commonly used medium in almost every stage of food and beverage production. It is used as an ingredient, as a coolant, and for washing. If the contaminated water is not properly treated, it can infuse pathogens directly into the product. The food and beverage manufacturing industries should mandate water quality testing along with the routine food testing to keep microbial contamination away from the facility.
What pathogens hide in food production water?
E. coli, Salmonella, Legionella, Listeria monocytogenes, hepatitis A, coliforms, and enterovirus are some of the possible bacteria and viruses that hide in the food production water. They frequently stick to internal surfaces as they enter into the facility through a pipeline, forming a sticky, protective layer called a "biofilm". They can continuously pollute passing streams of water because this biofilm protects them from conventional chemical sanitisers.
Table 1: Waterborne pathogens, their optimal environments, transmission, and associated diseases.
Pathogen | Optimal Environment | Linked Foods | Related disease | Resources |
Listeria monocytogenes | Wet, cold & harsh(Floor drains, chilling water, condensation pipes) | Ready-to-Eat (RTE) foods, dairy, salads, sprouts, melons, and seafood. | Listeriosis, a weakened immune system, and for pregnant women (miscarriage/stillbirth). | |
Escherichia coli (E. coli) | Wet, warm, and nutrient-rich HVAC lines, harvesting/processing equipment | Raw or undercooked meat, dairy, fruits, and vegetables | Hemorrhagic colitis, Hemolytic Uremic Syndrome (HUS) | |
Vibrio Cholera | Wet, warm, and alkaline | Seafood, water, and any fresh produce washed or cooled using contaminated water and ice | Cholera, watery stools, and severe vomiting and diarrhea | |
Salmonella | Dry or wet, it effectively grows with or without oxygen. HVAC vents, conveyor belts, dry-wet transition zones | Meat, raw eggs, undercooked beef, poultry, water, and raw milk | Salmonellosis, Typhoid fever, nausea, vomiting, diarrhea | |
Legionella | Cold, warm, & wet. Facility water lines, misting systems, and complex plumbing networks | No food. Aerosol contamination from water facility systems | Legionnaires (Pontiac fever, severe pneumonia) | |
Hepatitis A Virus | Grow and multiply in the human liver. Survive in hot, cold, acidic environments. | Raw shellfish, frozen berries, raw leafy greens, and ready-to-eat foods that are in contact with an infected food handler | Hepatitis A, jaundice, extreme fatigue, dark urine, abdominal pain, and acute liver inflammation. | |
Coliforms | Wet, warm, nutrient-rich. Condensation pipes, conveyor belts, gaskets. | Raw dairy products, ground meats, and any fresh produce washed using contaminated water | Gastroenteritis (severe stomach cramps, watery or bloody diarrhea, and vomiting) | |
Enterovirus | Wet and warm | Transmitted through the fecal-oral route. Fresh produce irrigated or washed with contaminated water, shellfish | Fevers and Hand, Foot, and Mouth Disease (HFMD) |
Important water testing standards as per the Bureau of Indian Standards (BIS) and WHO
By detecting physical, chemical, and microbiological pollutants, water testing standards protect public health. The main regulatory framework in India is the Bureau of Indian Standards (BIS IS:10500:2012), which closely collaborates with WHO recommendations to set maximum acceptable limits for drinking water in terms of physical, chemical, and biological aspects in drinking water. Some of the important parameters with their acceptable and permissible limits are highlighted below:
Table 2: The recommended limits for physical, chemical, biological, and radioactive parameters for drinking water by BIS and WHO.
Parameter | BIS water testing standards | WHO water testing standards |
Physical water quality limits | ||
pH | 6.5-8.5 (no permissible limits) | 6.5–8.5 |
Turbidity | 1 NTU (acceptable) 5 NTU (permissible) | < 0.5 NTU (for large municipalities) ≤ 0.2 NTU (Average) |
Total Dissolved Solids (TDS) | 500 mg/l (acceptable), 2000 mg/l (permissible) | < 600 mg/l |
Biological water quality limits | ||
E. coli and coliforms | 0 CFU/100 ml sample | 0 CFU/100 ml |
Cryptosporidium & Giardia | Absent in 10L of water | - |
Chemical water quality limits | ||
Chlorine | 0.2 mg/l (acceptable), 1 mg/l (permissible) | 5 mg/l |
Fluoride | 1 mg/l (acceptable), 1.5 mg/l (permissible) | 1.5 mg/l |
Nitrate (as NO₃) | 45 mg/l | 50 mg/l |
Toxic metals water quality limits | ||
Lead | 0.01 mg/l (no permissible limits) | 0.01 mg/l |
Mercury | 0.001 mg/l (no permissible limits) | 0.006 mg/l |
Arsenic | 0.01 mg/l | 0.01 mg/l |
Radioactive water quality limits | ||
Alpha emitters | 0.1 Bq/l (no permissible limits) | 0.5 Bq/l |
Beta emitters | 1.0 Bq/l (no permissible limits) | 1.0 Bq/l |
Why are culture methods failing water quality testing in food plants?
Food plants often require fast and accurate methods for food and water testing, as the facilities run shift-based production cycles every 8-24 hrs to meet the demand. Because the supply chain is fast, holding products for long periods in the inventory affects the product quality and shelf life. For food or water pathogen testing, culture methods take 48-72 hr and can yield false negatives. This results in a massive time lag, and the food or beverage products from the production often leave for distribution even before the results. This leads to public health concerns and expensive recalls. Another downside of the culture method is that a single extraction sample can’t be used to detect multiple targeted pathogens. Each target pathogen requires a specialised protocol and medium. On the other side, molecular methods such as real-time polymerase chain reaction (RT-PCR) save time and provide results within 2 hours and minimise the risk of false positives. This helps fast-moving food and beverage production lines to distribute faster with full confidence, eliminating the fear of expensive recalls.
RT-PCR water quality testing: how does it work?
RT PCR water quality testing can be done in 4 simple steps.
Sample filtration: The water sample is filtered, and the sediment is taken
DNA extraction: DNA is extracted using a Universal DNA extraction kit.
Amplification: Using extracted DNA, a master mix is prepared according to the target pathogen (E. coli, Salmonella, hepatitis A virus, Legionella, Enterovirus, Vibrio cholerae, Listeria, and run on the RT-PCR system.
Results: A positive or negative result is obtained
Building a Water Quality Testing Unit in Your Food Manufacturing Facility
In most of the food manufacturing units, the finished goods are usually tested rigorously, but the water that is used in almost every stage of the food processing is rarely questioned in the case of pathogen detection. To get a pathogen-proof facility, the water quality testing should cover these critical points.
Inlet water: The water that enters the facility directly from the municipal supply, which often comes treated. Testing at this point helps the units to understand the source of contamination.
Process water: The water that directly interacts with the food products. Monitoring the pathogen at this point helps to restrict the usage, as the contaminated water introduces pathogens onto the food products.
Output water: The wastewater or drainage water. Testing at this point gives an early warning of cross-contamination.
Post CIP (Clean-in-Place) water: The water after rinsing. Testing at this point protects the food products from contamination for the next production because this sample point has a high chance of biofilm formation.
Key takeaways:
Water quality testing: Testing of water for different parameters, which involves physical, chemical, biological/microbial, and radioactive parameters.
Major waterborne pathogens: E. coli, Hepatitis A virus, Vibrio cholerae, Listeria, coliforms, Salmonella, enterovirus, and Legionella.
Waterborne pathogens, related diseases, and limits set by BIS and WHO: Refer to Table 1 and Table 2.
Culture techniques vs. RT-PCR: RT-PCR reduces risks from manufacture to distribution by reducing the possibility of false negatives and producing results in two hours.
RT-PCR method for water testing: It involves sample filtration, DNA extraction, amplification, and results.
Critical points for water testing in a food plant: Inlet water, process water, output water, and post-CIP water.
FAQs
Q: Which pathogens must be tested in water for food production compulsorily?
A: The pathogens that must be compulsorily tested in water for food production are E. coli, coliforms, Hepatitis A virus, Salmonella, Legionella, Listeria monocytogenes, and Enterovirus.
Q: What is the major drawback of culture methods in water testing?
A: The culture method provides results in 48-72 hrs, and there is a chance of getting false negatives.
Q: What are FSSAI's water quality limits for E. coli in food manufacturing plants?
A: FSSAI mandates the complete absence (0 CFU/100 ml) of E. coli in the water sample.
Q: Who sets the water quality limits for food manufacturing plants in India and worldwide?
A: In India, FSSAI (Food Safety and Standards Authority of India) mandates the water quality limits set by BIS (Bureau of Indian Standards). Globally, the WHO (World Health Organization) publishes water quality guidelines; organizations like FAO (Food and Agriculture Organization) and Codex Alimentarius also provide global food standards, including water hygiene.
Q: What are the critical points for water testing in a food manufacturing plant?
A: There are 4 critical points in food manufacturing plants that are essential to monitor to ensure the food or beverage product is pathogen-free. They are inlet water, process water, output water, and post-CIP water.
Want a pathogen-free environment in your food manufacturing facility??
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