Unfiltered water carries the potential to make a person sick, depending entirely on the water source and the contaminants introduced to it. These contaminants fall into two broad categories: living microorganisms that cause immediate, acute illness and non-living chemical compounds that pose long-term health risks. Understanding the source and nature of these impurities is the first step toward safeguarding health.
Pathogens and Acute Illnesses
The most immediate danger in unfiltered water comes from microbial contaminants, which are living organisms that cause acute, or rapid-onset, sickness. These pathogens are often introduced into water sources through human or animal waste runoff. The resulting illnesses are collectively known as waterborne diseases, characterized primarily by gastrointestinal distress.
One major group is bacteria, which includes species like Escherichia coli (E. coli), Salmonella, and Campylobacter. The presence of E. coli is frequently used as an indicator of fecal contamination, suggesting that other harmful intestinal pathogens may also be present. Ingesting these bacteria typically causes symptoms such as stomach cramps, diarrhea, vomiting, and nausea.
Protozoa and parasites, such as Giardia and Cryptosporidium, are often more resistant to standard chlorine disinfection than bacteria. Cryptosporidium causes cryptosporidiosis, a diarrheal disease that can persist for over a month. Viruses, including Norovirus and Rotavirus, are also easily transmitted through contaminated water and cause diarrhea.
Non-Microbial Contaminants and Chronic Risks
Beyond immediate microbial threats, unfiltered water can contain non-living chemical contaminants that pose risks to long-term health. These substances rarely cause sudden sickness but instead accumulate in the body over years, leading to chronic health issues. This category includes heavy metals such as lead, arsenic, and mercury.
Lead often enters drinking water from the corrosion of old plumbing materials and fixtures, especially in older homes, and is known to cause neurological damage. Arsenic can occur naturally in groundwater in many regions, and its long-term consumption is linked to an increased risk of cancers of the skin, bladder, and lungs. Industrial waste and mining activities are also common sources for heavy metals like cadmium and copper, which can accumulate and affect organ function.
Synthetic organic compounds constitute another class of chemical contaminants, including pesticides, herbicides, and industrial solvents. These compounds enter water through agricultural runoff or improper waste disposal and may interfere with the body’s endocrine system. Exposure to these chemicals over time can contribute to organ failure, kidney damage, or an elevated cancer risk.
Determining Safety and Treatment Options
Determining the safety of unfiltered water requires a systematic approach, especially for private wells not subject to municipal treatment. Regular professional water testing is the only reliable way to detect the presence and concentration of contaminants, including heavy metals and organic compounds. Testing should be performed at least annually, or immediately if the water’s taste, smell, or appearance changes.
For immediate treatment of microbial threats, boiling water vigorously for at least one minute is a reliable method to kill bacteria, viruses, and protozoa. Chemical disinfection, using products like iodine or chlorine drops, is an alternative when boiling is not possible, though it is less effective against certain protozoa like Cryptosporidium. Neither boiling nor chemical treatment removes heavy metals or chemical pollutants.
Effective removal of non-microbial contaminants requires specialized filtration systems. Activated carbon filters remove chlorine, volatile organic compounds, and improve taste. Reverse osmosis systems are highly effective, removing a wide range of dissolved solids, including heavy metals and chemical residues. Ultraviolet (UV) purification is specifically designed to inactivate microbial pathogens like bacteria and viruses, preventing them from reproducing and causing infection.