The viruses in the water are enteroviruses (including poliovirus and other enteroviruses), hepatitis viruses, coronaviruses, and SARS coronaviruses.

The clinical manifestations caused by enteroviruses are complex and variable, and the same type of virus can cause different symptoms, and different types of viruses can cause similar clinical manifestations. The general symptoms are as follows: aseptic meningitis, encephalitis; acute myocarditis and pericarditis; epidemic chest pain; herpes angina; rash disease; respiratory infection; diarrhea in children.

Viral hepatitis can be generally divided into hepatitis A (infectious hepatitis or short-latency hepatitis) and hepatitis B (sero-hepatitis or latent hepatitis), and the pathological changes and clinical manifestations of the two are basically the same. The main clinical symptoms are loss of appetite, nausea, upper abdominal discomfort (or liver pain), fatigue, etc. Some patients have jaundice and fever, most of the liver is swollen, accompanied by liver damage. Hepatitis A virus (HAV) is a picornavirus that is morphologically distinct from other members of the same family.

In 1981, it was classified as enterovirus type 72. Recently, it has been classified into the Hepamavirus family because of its many characteristics different from those of enteroviruses. Hepatitis A virus is mainly excreted from the feces and transmitted orally. After the water source or food is contaminated, it may cause an explosive epidemic. The hepatitis virus is highly resistant to general chemical disinfectants and can survive for months or years in a dry or frozen environment. It can be inactivated by irradiation with ultraviolet light for 1 hour or cooking for more than 30 minutes. Chlorination has a certain inactivation effect.

Rotavirus is mainly transmitted through the oral-fecal route and can be spread by drinking or eating contaminated drinking water or food, or by exposure to contaminated objects. The outbreak of rotavirus disease in Colorado in 1981 was associated with pollution from municipal water supplies. Since 1982, several outbreaks of B-type rotavirus infecting hundreds of people have occurred in China, due to the contamination of drinking water by sewage. At the end of 2002, the first case of severe acute respiratory syndrome (SARS) in Guangdong Province was discovered. As of June 2003, SARS has spread to 380 countries and regions, with a total incidence of more than 8,000 cases. More than 800 people died. The patient usually has fever above 38 °C at the beginning, and is accompanied by chills, or headache, burnout and myalgia. The latter manifests as dry cough without sputum and difficulty breathing. The disease transmission route is mainly spread by close-range droplets, and can be transmitted through the mouth, nose and eyes through hand contact with respiratory secretions.