1. Asbestos

Many people do not expect asbestos to be in tap water, but it is still possible, especially in older homes where outdated pipes are used. Even though asbestos is banned, small fibers can find their way into the system when old cement pipes break down.

Asbestos exposure is known to cause serious health problems, including mesothelioma and other lung-related illnesses. Even tiny amounts can be harmful over time. If your home is older, or if your area has old piping systems, it is worth checking the condition of your water lines.

2. Legionnaires’ Disease

Legionnaires’ disease is a serious lung infection caused by Legionella bacteria, which can grow in warm or stagnant water systems. If the bacteria spread into the tap water supply, you may inhale it through mist or steam.

This infection can lead to pneumonia, high fever, chills, cough, headaches, chest pain, and shortness of breath. People with weak immune systems are more likely to develop severe symptoms. If your building has an outdated or poorly maintained water system, the risk may be higher.

3. Heavy Metals

Heavy metals such as lead, mercury, arsenic, and cadmium can enter groundwater naturally or through industrial activity. These metals can travel into tap water through corroded pipes or contaminated soil.

Even small amounts of heavy metals can cause harm. Symptoms depend on the type of metal but may include nerve problems, memory issues, stomach pain, muscle cramps, and diarrhea. Long-term exposure raises the risk of serious organ damage. Homes with older plumbing systems are more likely to experience metal contamination.

4. Bacteria and Parasites

Bacteria and parasites can enter the water supply from soil, sewage issues, or nearby farms. If you live in an area with wildlife, livestock, or agricultural runoff, the risk may be higher.

These organisms can cause stomach issues such as cramping, vomiting, nausea, and constipation. Repeated constipation can also contribute to hemorrhoids and rectal bleeding. People with weak immune systems may experience more severe or long-lasting symptoms. If your local water system has had contamination problems in the past, using a filter can provide extra protection.

5. Excess Fluoride

Fluoride is often added to tap water because it helps reduce tooth decay. In small amounts, it is useful. But too much fluoride may cause problems with the digestive system, immune system, or nervous system.

If your household already uses fluoride toothpaste or mouthwash, your total exposure may be higher than you realize. A simple water filter can help lower the fluoride levels if needed. Checking your local water report can also help you understand how much fluoride is in your supply.

6. PFAs

PFAs (per- and polyfluoroalkyl substances) are chemicals used to create non-stick, waterproof, and heat-resistant products. They do not break down easily, which is why they often end up in groundwater and public water systems.

Exposure to PFAs is linked to higher cholesterol, liver and kidney issues, immune system problems, and an increased risk of certain cancers. Water companies are required to report PFAs levels. Still, if you are concerned, installing a filter designed to remove PFAs is a good step.

7. Hepatitis A

Hepatitis A is a viral infection that affects the liver and spreads through contaminated food or water. It can reach tap water if the supply becomes exposed to small particles of fecal matter.

Symptoms include fever, nausea, loss of appetite, diarrhea, abdominal discomfort, dark urine, and yellowing of the eyes. Keeping your sewage system in good condition and using filtered water can help reduce your risk. Filters with proper certification can remove many contaminants linked to viral exposure.