How to Stop Your Motorhome Waste Tank from Smelling


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There’s nothing that quite takes away from travelling through some of the beautiful countries across Europe in your motorhome than nasty smells coming from your waste tank. A smelly waste tank can not only ruin the enjoyment of your trip but also create an unhealthy environment in your motorhome. Here, we’ll dive deep into how to stop your motorhome waste tank from smelling and ensure you enjoy every moment in your motorhome.

Causes of Waste Tank Odour

Stagnant Waste

One of the primary culprits behind the stench in waste tanks is the accumulation of stagnant waste. When waste is allowed to sit for prolonged periods without proper disposal, it begins to decompose.

This decomposition process releases a variety of gases, including methane and hydrogen sulphide, which have distinctively foul odours. These gases can become trapped within the tank, especially if it’s not ventilated adequately, leading to an increasingly unpleasant smell.

Inadequate Ventilation

Every waste tank needs to breathe. Proper ventilation allows the gases produced during the decomposition process to escape into the atmosphere rather than getting trapped inside. Without this escape route, the pressure and odour build up, leading to a more pungent smell inside the motorhome.

Furthermore, adequate ventilation also aids in the evaporation of moisture, another factor in waste decomposition and odour production.

Overuse of Chemicals

The market is flooded with chemicals that promise to break down waste and eliminate odours. However, their overuse or misuse can be counterproductive.

Some chemicals can kill off the beneficial bacteria that naturally break down waste. When these bacteria are absent, waste can take longer to decompose or might decompose in a way that produces even more pungent odours.

Additionally, the chemicals themselves can sometimes contribute to the odour problem if they’re not suitable for the specific waste or conditions in the tank.

Residual Waste Build-up

Sometimes, even after emptying the waste tank, a thin layer of residual waste can cling to the tank’s walls and floor.

Over time, this layer can harden and become a breeding ground for bacteria, leading to a continuous source of foul odours. Regular and thorough cleaning is essential to prevent this build-up.

Old or Damaged Seals

The seals on waste tanks and their connecting pipes are designed to prevent any leakage and escape of odours. However, with time and use, these seals can deteriorate or get damaged. A compromised seal can allow odours to seep out, even if the tank itself is clean.

External Factors

The surrounding environment can also play a role in waste tank odours. For instance, if a motorhome is parked in a place with high ambient temperatures, the heat can accelerate the decomposition of waste, leading to faster gas production and stronger odours.

Similarly, high humidity can prevent moisture in the tank from evaporating, creating a more conducive environment for bacterial growth and odour production.

Understanding the root causes of waste tank odours is crucial to effectively addressing and preventing them.

How to stop your motorhome waste tank from smelling

Proper Cleaning and Maintenance

Emptying the Tank Regularly

It’s crucial to establish a routine where you empty your waste tank frequently. This prevents the accumulation of stagnant waste.

As a general guideline, you should consider emptying the tank every 3-5 days of continuous use or whenever it’s about two-thirds full, whichever comes first. This frequency can vary based on factors like usage and weather conditions.

Using Non-Toxic Cleaners

Once you’ve emptied the tank, give it a thorough clean. Using natural cleaners like a mixture of vinegar and water can be effective.

These non-toxic solutions can break down residual waste without harming the natural bacteria in the tank or the tank’s material. This is an eco-friendly approach that also ensures the longevity of your waste system.

Deep Cleaning

At least once a season, or after a long trip, consider giving your waste tank a deep clean. This might involve filling it with a solution of water and a suitable tank cleaner, letting it sit for a few hours, and then thoroughly rinsing.

Ensuring Proper Ventilation

Installing Effective Vent Systems

A good vent system is vital for letting out the gases produced by waste decomposition. Make sure your motorhome’s waste tank has an efficient vent that is free from blockages. Some modern vent designs also help in drawing out the gases more effectively by using the vehicle’s motion to create a vacuum.

Avoiding Blockages

It’s common for vent pipes to get blocked by debris, bird nests, or even insects. Regularly inspect your vent system for any obstructions and clear them. Using mesh or screens can help prevent future blockages.

Using Natural Odour Eliminators

Baking Soda and Vinegar

This is a classic combination that works wonders in neutralising odours. Pouring a mixture of baking soda and vinegar into the waste tank and allowing it to sit for a few hours before rinsing can help keep odours at bay.

This combination also has a slight cleaning effect, helping to break down some of the residual waste.

Essential Oils

Essential oils are not just about masking the odours; many have antibacterial properties that can help in reducing odour-causing bacteria.

Drops of lavender, eucalyptus, or tea tree oil can be added to the tank after cleaning. These oils provide a pleasant smell and contribute to a healthier tank environment.

Regularly Inspect and Replace Seals

The seals in the waste system, especially around the toilet and the waste tank exit, play a crucial role in containing odours.

Over time, these can wear out or get damaged. Inspecting them regularly and replacing them when necessary can prevent unwanted odours from escaping.

Use Bioactive Treatments

Instead of chemicals, consider using bioactive treatments. These treatments contain bacteria and enzymes that break down waste in an eco-friendly manner, producing less gas and odour in the process.

By adopting these solutions and integrating them into your motorhome maintenance routine, you can significantly reduce, if not entirely eliminate, the challenges of waste tank odours and ensure a pleasant journey every time.


Maintaining an odour-free waste tank is essential for a pleasant and healthy motorhome experience. By following the above recommendations, you can prevent waste tank odours and enjoy a fresh and clean environment on your adventures.

Frequently Asked Questions

How often should I empty my waste tank?

It is recommended to empty your waste tank every 3-5 days of use.

What can I use to clean my waste tank naturally?

Vinegar and water are excellent natural cleaners for your waste tank.

How can I prevent my waste tank vent from getting blocked?

Regularly check your vent pipes for obstructions, such as leaves or bird nests, and remove them to ensure proper airflow.

Can I use essential oils to mask waste tank odours?

Yes, essential oils like lavender or eucalyptus can be used to mask odours. Add a few drops of essential oil to your waste tank after cleaning it.

Should I seek professional help if my waste tank still smells?

If you have tried all the recommended solutions and still experience odours, it may be time to seek professional help.

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