Unpleasant odours in water can have many different causes. The smell may be described as musty, earthy, chemical, sewage-like, mould-like or simply unusual. In many cases the cause is related to natural processes in the source water, but odour changes may also indicate problems in wells, plumbing systems, water heaters or other equipment.
Humans are extremely sensitive to odour compounds and can often detect changes long before they become visible in a water analysis. A new or increasing odour should therefore be considered an important indication that water quality or system performance has changed. Even if the cause does not necessarily represent a health risk, it is generally recommended to identify the source.
Common Causes
- Biofilm and Microbiological Activity
- Organic Matter in Source Water
- Algae and Cyanobacteria
- Stagnant Water in Pipes or Tanks
- Water Heater Issues
- Surface Water Intrusion
- Chemical Contamination or Process Issues
Common Symptoms
- Musty or Stale Odour
- Mould-Like Odour
- Chemical Odour
- Odour Mainly Present in Hot Water
- Intermittent Odour Problems
- Taste Changes Accompanying Odours
Common Treatment Methods
- Water Analysis
- Activated Carbon
- Ozone
- UV Disinfection
- System Cleaning and Flushing
- Inspection of Wells and Pipework
Example Treatment Trains
Raw Water
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Activated Carbon
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UV Disinfection
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Drinking Water
Raw Water
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Ozone
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Activated Carbon
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UV Disinfection
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Drinking Water
Did You Know?
Odour issues are often detected long before other water quality problems become apparent. Humans can detect certain odour compounds at concentrations far below levels that cause visible changes in the water. For this reason, changes in odour are often among the earliest signs that something has changed in the water source or treatment system.
If water suddenly develops a new or noticeably stronger odour, the cause should always be investigated. Although many odour issues have natural causes, changes may also be related to leaking wells, surface water intrusion, biofilm growth, equipment faults or other issues requiring corrective action. Water analysis combined with technical inspection is often the fastest way to identify the source of the problem.