How to tell if your Durham Region tap water contaminated

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How to tell if your Durham Region tap water contaminated

Contaminated tap water is a health risk to everyone. Below are signs to help you determine if  tap water is contaminated

If the water coming from your tap is cloudy, you might believe it is contaminated. However, cloudiness can be a common occurrence in tap water and does not necessarily indicate contamination.

If you fill a glass with water and let it sit for a few minutes, chances are the water will clear from the top to bottom. This indicates that the cloudiness was simply a substantial amount of tiny air bubbles.

If the water does not clear, however, it could indicate the presence of dirt, sand, clay, or methane gas. See below for more on this, along with other signs that could be cause for concern.

Cloudy, Foamy Water

Water that is safe to drink should ideally be clear, odourless, and void of any strange taste. Many municipal water systems do not filter out minerals and other naturally occurring substances from drinking water. These harmless compounds can sometimes give water a cloudy or foamy appearance, which normally disappears over time. However, if the cloudiness does not settle, it could signal the presence of unsafe pathogens or chemicals.

Unusual Taste

If your water has a fishy, oily, bitter, or metallic taste, it may be time to look into buying a filter. A metallic taste could signal the presence of excess iron or copper.  

Rusty pipes can release metals like iron, manganese, zinc, and copper into local water supplies, giving the water a salty or metallic taste.

Chlorine Smell

Water that smells like bleach could be a sign of excess chlorine in your local system. Chlorine is added to public water supplies to remove bacteria or harmful microorganisms.  

When it mixes with other organic compounds, harmful byproducts can be created. One of these byproducts, a group of chemicals known as trihalomethanes (THMs), has been linked to kidney problems and increased cancer risk. Haloacetic acids (HAAs), can also cause skin irritation and could also increase cancer risk.

Low levels of chlorine in the water system can also expose people to a parasite called giardia. This could result indiarrhea, cramps, and nausea.

While some chlorine in your water is okay, there is likely too much of it if you notice a strong smell. A water-filtration system can help eliminate the issue.

Sulfer Smell

The smell of rotten eggs likely means you have a sulfur problem. Hydrogen sulfide, a colourless gas that can naturally occur in groundwater, converts to sulfate when exposed to certain bacteria. Although it is not typically harmful, it can make water unpleasant to drink. As with chlorine, the smell of sulfur can be eliminated with a water filter.

Fishy Smell

Fishy-smelling water could signal an excess of barium, a naturally-occurring chemical that can seep into a water supply through drilling or manufacturing. The presence of barium above the CEPA (Canaidian Environmental Protection Act) could cause increased blood pressure, muscle weakness, or kidney, liver, and heart damage.

Water that smells fishy might also contain cadmium, a chemical found in lead and copper ores. Cadmium often leaches into pipes through industrial waste. Exposure to elevated levels of cadmium in drinking water can cause kidney, liver, and bone damage.

Unusual smells that are a result of bacterial overgrowth are normally treated with a UV water treatment or well chlorination. This eliminates microorganisms and coliform bacteria.

Gas odor    

Smelling petroleum in your water may mean that your water is contaminated with fuel, gasoline additives, or petroleum. This can have negative health effects in the long and short term, depending on exposure.  

Low Water Pressure

If the water pressure coming from the taps is less than normal, it could indicate clogged pipes. While the culprit could be food or grease, it could also be caused by pipes that have become corroded over time. When this happens, the pipes can fill up with sediment and scale. The only solution to this type of problem is running new copper or PVC plumbing throughout the house.  


Water that is orange or brown could contain excess iron, manganese, or lead. It could also signal the presence of rust, which can breed bacteria. Common treatments for iron include water softeners, filtration tanks, and aeration systems.

Water tinged with green or blue could contain elevated levels of copper.

Yellow water could signal the presence of chromium-6, the cancer-causing chemical that resulted in a lawsuit filed by clean water advocate Erin Brockovich. It might also be a sign of a buildup of iron, manganese, copper, or lead.

If your water is on a public system and only shows a yellow tint when running cold water, it could be a sign that your utility is clearing out its pipes.  

Dirt & Sediment  

If you have ever noticed dirt, sand, clay, or other sediments in your tap water or sink basin, it might be a good idea to install a point-of-use sediment filter. While most of these particles are not dangerous, they are certainly not welcome by those drinking the water.  

Spots, Stains, and Scale

Some municipalities have naturally “hard” water. This is water that contains a high percentage of dissolved minerals like calcium and magnesium. Hard water is not dangerous, but it can prevent suds from lathering, reducing the effectiveness of dish soap and hand soap, along with laundry detergent.

Hard water is also a culprit of leaving spotted scale deposits on dishes and glassware. More importantly, these deposits can shorten the lifespan of your hot water heater, boiler, and other appliances. Installing a water-softening system to remove excess minerals will solve these issues.

Stiff laundry, soap scum, or mineral buildup  

If your clothing is stiff or scratchy after being washed, you might be dealing with hard water due to high calcium and magnesium levels. Other signs are mineral buildup in tubs or showers, soap not lathering properly, and issues with your water heater's performance. Water softeners are a common solution for these types of hard water related problems.

Rusted Silverware  

Tarnished and rusted silverware often means there is too much iron in your water. Iron adheres to silverware while being washed, then oxidizes (rusts) once the silverware is exposed to open air.

If your water is clear and void of any orange or brown colour, it is unlikely that toxic amounts of iron are present. However, much like the silverware, the inside of your pipes and faucets may begin rust with each water use, resulting in future repair or replacement.

The Invisible Ones

Many contaminants, including arsenic and nitrates, are not visible to the naked eye. It is not uncommon for a single drinking water system to contain more than one hazardous chemical.  

Even a reverse osmosis system can trap contaminated water in its filters. This makes it difficult for individuals to evaluate their overall health risk.  


It is a priority to know your water source and read the water quality reports from your local utility.

Public Health Ontario (PHO) provides testing of water samples collected from private drinking water systems, such as a well and other private drinking water systems (ie. water from cisterns, treated lake water, etc) PHO tests for the bacterial contaminants E.coli and total coliforms. You can learn more about well water testing at PHO. You can also order a sample collection kit on their Well Water Testing page.

If you have a specific question about water quality or testing, or would like information on where to go to test for other contaminants, below is a list of contacts.

Contact a Public Health Unit if you:

  • Suspect surface water or human or animal waste has entered your well
  • Require a private drinking water sample collection kit to test for bacterial contamination
  • Have questions about the results of your test
  • Have questions about other environmental testing, including testing for chemical contaminants

Contact a licensed laboratory if you:

Contact a licensed well contractor if you:

  • Are concerned that your well is poorly constructed
  • Your well needs upgrading or maintenance
  • Refer to the Ministry of Environment, Conservation and Parks Directory of Licensed Well Contractors or searchfor water well drilling and services in your local area

Contact a licensed plumbing inspector if you:

  • Need to have your plumbing system professionally inspected
  • Contact your local Public Health Unit for a list of available professionals in your area

Ministry of Environment, Conservation and Parks (MECP)   - contact MECP for information related to:

Additional Resources: