Introduction
A fuel, diesel, oil or petroleum smell in water should always be taken seriously. Unlike many common taste and odour problems, a petroleum-like smell may indicate contamination from fuels, oils, solvents or other petroleum products.
In private wells, the source may be a leaking fuel tank, fuel spill, contaminated groundwater or industrial activity. In rare cases, plumbing materials, treatment equipment or nearby fuel storage can also contribute to unusual odours.
If water smells strongly of petrol, diesel, fuel oil or solvents, it should not be used for drinking, cooking or food preparation until the cause has been identified.
What Does a Petroleum Smell Resemble?
People describe petroleum contamination in different ways.
Common descriptions include:
- Petrol smell
- Gasoline smell
- Diesel smell
- Fuel oil smell
- Kerosene smell
- Chemical solvent smell
- Oily odour
- Hydrocarbon smell
The smell may be noticeable in:
- Drinking water
- Hot water
- Cold water
- Water from all taps
- Water drawn directly from a private well
Is a Fuel Smell Dangerous?
Potentially, yes.
Petroleum products contain various hydrocarbon compounds that are not normally present in drinking water. Even when concentrations are low, many of these substances produce noticeable taste and odour problems.
A petroleum smell should be investigated as soon as possible, particularly if:
- The smell appeared suddenly
- A fuel spill has occurred nearby
- An underground tank is present
- Water shows an oily sheen
- Neighbours experience similar problems
- The property uses a private well
Common Causes
Leaking Fuel Storage Tanks
One of the most common causes is leakage from:
- Heating oil tanks
- Diesel tanks
- Underground storage tanks
- Farm fuel tanks
- Vehicle or equipment storage systems
Leaking fuel can gradually migrate through soil and reach groundwater.
Typical signs
- Strong diesel or heating oil smell
- Odour becomes worse after groundwater changes
- Nearby fuel storage present
Fuel Spills
Accidental spills can affect groundwater and wells.
Possible sources include:
- Refuelling accidents
- Vehicle accidents
- Industrial spills
- Agricultural fuel handling
- Heating oil deliveries
Contamination may occur immediately or appear months later, depending on local geology and groundwater conditions.
Industrial Contamination
Some industrial activities use fuels, oils, solvents and hydrocarbon-based chemicals.
Possible sources include:
- Workshops
- Service stations
- Transport depots
- Industrial sites
- Manufacturing facilities
In some cases, contamination may originate from historical activities that occurred years earlier.
Contaminated Groundwater
Petroleum contamination can travel with groundwater and affect wells located some distance from the original source.
This is particularly important in areas with:
- Shallow groundwater
- Sandy soils
- Fractured bedrock
- Historic industrial activity
Plumbing or Equipment Issues
Although less common, some odours originate within the building rather than the groundwater.
Possible sources include:
- New plastic components
- Flexible hoses
- Pressure tanks
- Water treatment equipment
- Plumbing materials
If only one tap is affected, the cause may be local rather than originating from the water source itself.
How to Troubleshoot
1. Determine whether all taps are affected
Check:
- Kitchen tap
- Bathroom tap
- Outdoor tap
- Cold water
- Hot water
If every tap is affected, the problem is more likely to involve the incoming water supply.
2. Compare hot and cold water
If only hot water smells, investigate:
- Water heater
- Storage tank
- Internal plumbing
If both hot and cold water smell, the source may be the raw water supply.
3. Look for recent changes
Consider whether any of the following have occurred:
- Fuel deliveries
- Excavation work
- Construction activity
- Nearby spills
- Flooding
- Changes in groundwater levels
These events may help identify the source.
4. Check for nearby fuel sources
Inspect the area around the property for:
- Heating oil tanks
- Diesel tanks
- Fuel storage sheds
- Vehicle workshops
- Old underground tanks
Even an old, forgotten tank can become a source of contamination.
5. Test the water
If the smell appears to originate from the water itself, laboratory testing should be performed before selecting treatment equipment.
Water analysis may include:
- Petroleum hydrocarbons
- Volatile organic compounds (VOCs)
- BTEX compounds (benzene, toluene, ethylbenzene and xylene)
- General water quality parameters
Treatment Options
The correct solution depends on the source and severity of contamination.
For petroleum contamination, identifying and eliminating the source is usually more important than installing treatment equipment.
Fuel Tank Leakage
If a leaking fuel tank is identified, the source should be corrected immediately.
Typical solution path
Confirm contamination
→ Locate leak
→ Repair or remove tank
→ Assess groundwater contamination
→ Retest water
In many cases, remediation of the contamination source is required before treatment equipment can be considered.
Fuel Spill Contamination
Where a spill has affected groundwater, cleanup and remediation may be necessary.
Typical solution path
Water analysis
→ Identify contamination source
→ Spill cleanup
→ Groundwater assessment
→ Follow-up testing
Water treatment alone may not provide a complete solution if contamination continues to enter the groundwater.
Activated Carbon Treatment
Activated carbon is often used to reduce petroleum-related taste and odour compounds.
Typical treatment system
Raw water
→ Sediment filter
→ Activated carbon filter
→ Distribution system
| Treatment step | Function |
|---|---|
| Sediment filter | Removes particles and protects carbon media |
| Activated carbon | Reduces many petroleum-related taste and odour compounds |
Carbon filtration can improve water quality but may require regular media replacement.
Air Stripping and Aeration
Some volatile petroleum compounds can be removed through aeration or air-stripping systems.
These systems are typically used for:
- Volatile organic compounds
- Gasoline-related contamination
- Solvent contamination
System design depends on water quality and contaminant levels.
Advanced Treatment Systems
Where contamination levels are significant, multiple treatment technologies may be required.
Example treatment chain
Raw water
→ Sediment filter
→ Activated carbon
→ Additional treatment (if required)
→ Distribution
Treatment selection should be based on laboratory analysis rather than odour alone.
Municipal Water with a Fuel Smell
A fuel or petroleum smell in a municipal water supply is unusual.
If multiple neighbouring properties experience the same issue, contact the water supplier immediately.
Do not assume that a household filter will solve the problem before the source has been investigated.
Which Treatment Is Appropriate?
| Cause | Typical solution |
|---|---|
| Leaking fuel tank | Repair or remove source |
| Fuel spill | Cleanup and remediation |
| Contaminated groundwater | Source investigation and treatment |
| VOC contamination | Aeration or specialised treatment |
| Petroleum taste and odour | Activated carbon filtration |
| Plumbing component odour | Replace affected component |
| Unknown source | Water analysis first |
When Should Water Testing Be Performed?
Water testing is strongly recommended when:
- A petroleum smell is present in the water itself
- An oily sheen is visible
- The odour appeared suddenly
- Fuel storage exists nearby
- A spill has occurred
- A private well is affected
Testing is generally the best starting point for selecting an appropriate solution.
Frequently Asked Questions
Why does my water smell like diesel?
Possible causes include fuel contamination, leaking storage tanks, contaminated groundwater or nearby spills. Water testing is normally required to determine the cause.
Can activated carbon remove a fuel smell?
Activated carbon can often reduce petroleum-related taste and odour compounds, but it may not address the source of contamination.
Is a petroleum smell common in municipal water?
No. Fuel and petroleum odours are uncommon in properly treated municipal water supplies.
Can an old fuel tank affect a well?
Yes. Leaking underground or above-ground fuel tanks can contaminate soil and groundwater and may affect nearby wells.
Should I continue drinking water that smells like petrol?
If the smell appears to originate from the water itself, the cause should be investigated before the water is used for drinking or cooking.
Conclusion
A fuel or petroleum smell in water is uncommon and should be investigated. Possible causes include fuel spills, leaking storage tanks, contaminated groundwater and other hydrocarbon sources. In private wells, water testing is usually the first step toward identifying the source and selecting an appropriate solution. While activated carbon can often reduce petroleum-related tastes and odours, correcting the source of contamination is typically the most important long-term measure.