| Type | Contaminant | Max. Contaminant Level Goal (ppm) | Max. Contaminant Level (ppm) -or- Required Treatment Technique | Potential Health Effects from Long-Term Exposure Above the MCL (unless specified as short-term) | Sources of Contaminant in Drinking Water | Consumer Treatment Method | Official Sources |
| Microorganisms | Viruses (enteric) | 0 | Treatment Technique (99.9% removal/inactivation) | Gastrointestinal illness (such as diarrhea, vomiting, and cramps) | Human and animal fecal waste | Boiling water, UV light treatment, nanofiltration, reverse osmosis, distillation | CDC, CDC, EPA |
Viruses, particularly enteric ones, pose a significant threat to the safety of drinking water worldwide. As major causes of waterborne and water-related diseases, enteric viruses can contaminate water sources through human and animal waste, subsequently leading to the infection of individuals who come into contact with or consume the tainted water. Ensuring that these viruses are identified and removed or inactivated from our drinking water supply is imperative to maintaining public health and reducing the spread of various illnesses.
In the United States, regulations require the removal or inactivation of 99.99% of enteric viruses through approved treatment techniques, though specific virus families are not individually regulated. Meanwhile, Canada’s proposed guideline focuses on a health-based treatment goal for drinking water, which calls for a minimum 4-log, or 99.99%, removal and/or inactivation of enteric viruses. This guideline acknowledges that depending on the source water quality, a greater log reduction may be required. The development of sensors to detect infectious viruses in drinking water will not only benefit from these regulations and studies but is also necessary for ensuring safe, potable water for all communities.
Viruses (Enteric) in Drinking Water
Enteric viruses are a group of pathogenic microorganisms that primarily cause gastrointestinal illnesses. These viruses include rotavirus, adenovirus, norovirus, enterovirus, and astrovirus. They are a major concern for public health, as they contaminate drinking water sources through human and animal fecal matter.
Contamination of drinking water with human enteric viruses can lead to serious health issues, such as vomiting, diarrhea, meningitis, myocarditis, and encephalitis. Rotaviruses, for example, are responsible for a significant number of severe diarrhea cases in children worldwide. Sewage and wastewater discharge are common sources of enteric virus contamination in water, and other viruses like poliovirus, hepatitis A virus, caliciviruses, and polyomavirus can spread through the same routes.
Water quality plays a crucial role in minimizing the risk of enteric virus infection. Adequate treatment of raw water and proper maintenance of treated drinking water systems can significantly reduce the presence of pathogenic microorganisms, including enteric viruses. Detection methods, such as real-time PCR, help monitor water contamination and ensure that drinking water meets safety standards.
Although less common, some other viruses like hepatitis E, JC virus, and reovirus can potentially contaminate drinking water sources. These relatively rare waterborne viruses can cause severe symptoms or aggravate pre-existing conditions in affected individuals.
In addition to proper water treatment and monitoring, the control of viral shedding from infected individuals is essential in preventing the spread of enteric viruses. This includes adequate sanitation and hygienic practices, especially in areas with inadequate sewage and wastewater management systems.
Enteric virus outbreaks can occasionally occur due to contaminated drinking water, such as norovirus GI or sapovirus infection. These incidents highlight the importance of a comprehensive approach to water quality management, encompassing water treatment, contamination detection, and hygienic practices to protect public health.
How to Test for Viruses (Enteric) in Drinking Water
Testing for enteric viruses in drinking water is essential to ensure public health and safety, as these viruses can cause illnesses such as gastrointestinal diseases, hepatitis, and meningitis. There are various sources of water that can be contaminated with enteric viruses, including surface water, groundwater, and drinking water.
One commonly used method to identify and detect microbial contaminants in drinking water is through the use of bacterial indicators, such as Escherichia coli (E. coli). E. coli is used as an indicator for the presence of enteric viruses because it is often found in human and animal fecal waste, which can be a significant source of viral contamination in water sources. However, it is worth noting that studies dispute the overall effectiveness of this method, and encourage supplementing bacterial indicators with other tests for enteric viruses.
The U.S. Centers for Disease Control and Prevention (CDC) provides guidelines for testing drinking water for viral contaminants. A commonly used approach involves the following steps:
- Collection and concentration of water samples: Water samples are collected from the source, such as surface water or groundwater. The samples are then concentrated to increase the likelihood of detecting any present viruses.
- Extraction and purification of viral particles: The concentrated water samples are processed to extract and purify viral particles from potential contaminants.
- Detection of viral particles: Techniques such as polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA) can be used to detect the presence of specific enteric viruses in the samples.
It is important to note that testing methods may have limitations, such as the inability of an antibody to target all possible strains of the virus under study or all enteric viruses in water samples. To achieve accurate results, it is crucial to use reliable testing methods and perform regular monitoring of water sources for viral contamination.
Overall, testing for enteric viruses in drinking water is a vital aspect of maintaining public health. By employing bacterial indicators like E. coli and adhering to guidelines provided by the CDC, waterborne contaminants can be effectively detected and managed.
How to Remove Viruses (Enteric) from Drinking Water
Boiling Water
Boiling water is a simple and effective method to remove enteric viruses from drinking water. Heat the water to a rolling boil and continue boiling for at least one minute to ensure elimination of most waterborne diseases and viruses. During the boiling process, water reaches a high enough temperature to inactivate viruses, rendering them harmless.
UV Light Treatment
UV light treatment is another effective water disinfection method. Ultraviolet (UV) radiation inactivates viruses by damaging their genetic material, preventing them from reproducing or infecting humans. UV disinfection is recommended for water with low turbidity, as high turbidity can reduce the efficiency of the process.
Nanofiltration
Nanofiltration is a water filtration process that can remove enteroviruses by forcing water through a filter with pores smaller than the viruses themselves. These filters have pores measuring around 0.001 micron, which effectively blocks viruses from passing through. This method is suitable for both municipal water treatment plants and residential filtration systems.
Reverse Osmosis System
Reverse osmosis (RO) systems use pressure to force water through a semi-permeable membrane with very small pores, typically around 0.0001 micron, effectively removing most viruses, including enteric viruses. RO systems require periodic maintenance to guarantee their effectiveness, but they have been proven to provide a high level of virus reduction in drinking water.
Distillation
Distillation involves boiling water until it evaporates, and then condensing the resulting steam back into liquid form. During this process, contaminants like enteric viruses are left behind in the original container. Distillation can effectively remove enteric viruses from drinking water to ensure a safe supply for consumption.
How Do Viruses (Enteric) Get into Drinking Water
Enteric viruses, including adenoviruses, can contaminate drinking water through various pathways, posing a risk to human and animal health. These viruses can cause gastrointestinal and respiratory infections and are primarily transmitted through the fecal-oral route.
One significant source of contamination is untreated or inadequately treated sewage. When raw sewage or partially treated wastewater is discharged into water sources such as springs, rivers, dams, or marine estuaries, waterborne enteric viruses can enter the water supply and affect both surface water and groundwater sources. This leakage of sewage can occur due to infrastructure issues, natural disasters, or other factors leading to the unintentional mixing of wastewater with drinking water sources.
Another notable contributor to enteric virus contamination in drinking water is agricultural runoff. This occurs when heavy rainfall or irrigation causes water to flow over agricultural land, carrying animal waste and potentially virus-laden fecal matter into nearby water sources. Similarly, stormwater runoff and snowmelt events can introduce fecal contamination and enteric viruses into water supplies by washing animal and human waste into rivers, lakes, and reservoirs.
As a result of these contamination events, drinking water sources may become compromised, even in industrialized countries where bacterial indicators of fecal contamination may be absent. Therefore, it is crucial to include virological analysis in the routine control of water and food supplies to minimize public health risks associated with enteric virus exposure.
Effects of Viruses (Enteric) on the Human Body
Enteric viruses are a group of viruses that affect the gastrointestinal system, leading to a variety of symptoms and illnesses. Some common types of enteric viruses include rotaviruses, enteroviruses such as polioviruses, coxsackieviruses, and hepatitis A virus. These viruses can be transmitted through contaminated food, water, or contact with infected surfaces.
Gastroenteritis is one of the most common manifestations of enteric virus infections. Symptoms include diarrhea, vomiting, and abdominal pain. This can in-turn lead to dehydration, especially in children or the elderly. In addition to gastroenteritis, enteric viruses may also cause hepatitis, such as hepatitis A, which results in liver inflammation and can have long-term consequences like liver cirrhosis.
Enteroviruses can also lead to a wide range of other symptoms and diseases, such as meningitis, myocarditis, and encephalitis. Coxsackieviruses, for example, can cause hand, foot, and mouth disease in children. Polioviruses are well-known for causing paralysis, although this is now rare due to vaccination programs.
Some enteric viruses, such as polyomaviruses, have been linked to cancer, as their capsid proteins can interact with host oncogenes, resulting in the transformation of healthy cells into cancerous ones. However, more research is needed to fully understand the mechanisms and extent of this association.
Influenza and coronaviruses can also be found in water, though they are primarily respiratory viruses rather than enteric. Their presence in water supplies can still pose a risk if ingested or inhaled via aerosol droplets.
The overall morbidity and mortality associated with enteric viruses vary, depending on factors such as the type of virus, the individual’s immune system, and access to healthcare. While many infections caused by enteric viruses can be self-limiting and resolved without intervention, severe cases may require hospitalization and treatment to manage symptoms and complications.
In conclusion, enteric viruses in drinking water can lead to various health problems ranging from gastroenteritis to more severe illnesses like meningitis, myocarditis, and encephalitis. Ensuring access to clean water and proper sanitation is vital to prevent the transmission and spread of these viruses.
Conclusion
In summary, enteric viruses in drinking water pose a significant threat to public health, causing waterborne diseases and affecting the quality of water sources. These viruses are primarily transmitted through the fecal-oral route and can lead to severe gastrointestinal illness, especially in vulnerable populations such as children and the elderly.
Effective measures must be implemented to ensure safe drinking water, aimed at both eliminating and preventing enteroviruses from contaminating water supplies. Proper sanitation and hygiene practices are crucial in reducing the risk of waterborne virus infections and subsequent disease outbreaks.
Seasonal variations, such as the dry season and rainy season, play a significant role in the presence and proliferation of enteric viruses in water sources, affecting the overall water quality. Therefore, monitoring and surveillance efforts should consider these fluctuations to ensure appropriate actions are taken to maintain safe drinking water supplies.
Waterborne disease outbreaks related to enteric viruses not only have severe impacts on public health but also result in substantial economic losses. The implementation of effective treatment technologies, such as tangential flow filtration and others, is critical to reduce and eliminate enteric viruses in water sources. Additionally, vaccination programs for various enteric viruses can also aid in reducing the overall burden of disease in affected populations.
Furthermore, continuous tracking and monitoring of water quality parameters, such as temperature and total coliforms, play an essential role in understanding the correlation between microbial agents and waterborne illnesses. Consequently, a comprehensive approach involving multiple aspects, from proper sanitation and hygiene measures to the implementation of advanced treatment technologies, is necessary to reduce the risk of enteric viruses in drinking water and minimize the potential impact on public health.
