Turning on your tap and being greeted by an unpleasant odour is not reassuring. Whether it smells like rotten eggs, mould, chlorine or even metal, a bad smell in tap water is often a sign of imbalance, contamination or an inadequate filtration system.

These odours can have various causes: ageing pipes, bacteria, decomposing organic matter or municipal chemical treatments. While some are not immediately dangerous, others may indicate more serious problems.

In this article, we review the main undesirable odours, what causes them and possible solutions to remedy them, along with their limitations. Because, ultimately, if the ideal solution existed... we wouldn't have to ask the question. (Spoiler: it does exist.)

Should we be concerned about the smell of water?

A bad smell in the water does not always mean immediate danger, but it should never be ignored. In most cases, these odours are not directly harmful to health. However, they can reveal a deeper problem: bacterial contamination, corrosion of pipes, or chemical imbalance.

For example, a sulphur smell can indicate the presence of gas-producing bacteria, while the smell of chlorine, although harmless in small doses, reflects intensive chemical treatment of the water. Even metallic or musty odours can indicate poor water quality or a need for maintenance.

In summary: if your water has a strange smell, it is best not to take any risks. A water quality test is always recommended to assess its safety and take the appropriate measures.

The main causes of bad-smelling water

Several factors can alter the smell of drinking water. Here are the most common ones.

  • A sewer smell
    🌪️

    A sewer smell in the water can come from bacteria caused by residue in the sink or stagnant water in the water heater. This unpleasant smell becomes stronger if the appliance has been turned off for a long time, promoting bacterial growth.

  • A smell of rotten eggs🥚

    A smell of rotten eggs in water often indicates the presence of sulphur bacteria or hydrogen sulphide. Although these bacteria are not dangerous on their own, they promote the growth of other harmful organisms. High concentrations can be toxic, so it is not advisable to consume this water.

  • A musty smell🧫

    Water should have a fresh smell, not a musty or mouldy one. If it does smell musty or mouldy, this may indicate contamination by organic matter.

  • A metallic smell🔩

    A metallic smell in water can come from corrosion in old pipes, releasing iron, copper or zinc. A pH that is too low can also accentuate this smell by accelerating the degradation of metals in the plumbing.

  • A fishy smell🐟

    A fishy smell in the water may indicate the presence of bacteria or decomposing organic matter, such as leaves or vegetation, similar to that found in ponds or lakes.

  • The smell of a swimming pool 🏊

    A swimming pool smell in the water often indicates the presence of chlorine, a disinfectant commonly used in municipal water systems. Although effective and generally safe for humans, it can alter the smell and taste of the water.

Solutions to improve the smell of your water

Fortunately, there are several simple options for improving the smell of your tap water.

Du vinaigre et du bicarbonate de soude pour la mauvaise odeur de l'eau

Sewer odour

You can pour baking soda followed by vinegar down your drains, or clean the siphons to eliminate the bacteria responsible. If the odour is coming from the water heater, it may need to be drained.

However... these methods are often temporary: the odours return as soon as the bacteria reform, especially in older installations.

chauffe eau qui peut causer la mauvaise odeur de l'eau

Smell of rotten eggs

Having your water tested, disinfecting your water heater, or using activated carbon filters can reduce sulphur odours.

However... these solutions are not always effective in the long term, and some filters need to be replaced very frequently to remain effective.

Rincer les canalisations pour la mauvaise odeur de l'eau

Musty or stale odour

Flushing pipes, maintaining reservoirs and ensuring that no organic matter contaminates the water can help.

However... this only addresses the apparent source of the problem. If the contamination comes from the groundwater or infrastructure, these efforts will have limited impact.

Installation de filtre par un plombier pour la mauvaise odeur de l'eau

Metallic odour

Installing a water softener or specialised filter can reduce traces of metals in the water. Correcting the pH can also limit corrosion.

However... these installations are expensive, sometimes complex to maintain, and only work on certain types of metals.

Analyser l'eau de son robinet à cause de la mauvaise odeur qu'elle a

Fishy smell

Testing the water and cleaning the collection system can eliminate the organic matter responsible.

However... bacteria and debris can quickly return, especially if the water source itself is compromised.

Charbon actif dans la carafe pour filtrer et pour la mauvaise odeur de l'eau

Chlorine smell (swimming pool)

Using an activated carbon filter or letting the water stand before consumption helps to dissipate chlorine.

However... this does not always work effectively, especially if the chlorine concentration is high, and it does not remove other contaminants present.

Getting rid of unpleasant odours in water is a good thing, but it does not guarantee that it is safe to drink. This is particularly true for rainwater, well water or water from a poorly controlled network. Even water that appears clear, with no suspicious odour or taste, may contain invisible but dangerous microorganisms:

  • Bacteria (such as E. coli or salmonella)
  • Viruses (rotavirus, norovirus, etc.)
  • Protozoa (giardia, cryptosporidium, etc.)

These pathogens can cause sometimes severe illnesses, especially in vulnerable people. In this case, filtering the water is not enough: it must be purified, i.e. the threats invisible to the naked eye must be eliminated.

Water contamination

When the source of your water is uncertain, you need more than just aesthetic filtration. Water may appear perfectly clean while harbouring viruses, bacteria or even microplastics.

The ORISA® water purifier is a self-contained solution, requiring no electricity or chemicals, that transforms potentially contaminated water into safe, drinkable water. Thanks to its cutting-edge technology:

  • It eliminates 99.999999% of bacteria (e.g. E. coli)
  • 99.999% of viruses (e.g. rotavirus, norovirus)
  • And retains protozoa and microplastics

Equipped with a high-performance ultrafiltration membrane, it can treat up to 20,000 litres of water, providing several years of autonomy for a family.

Originally designed for humanitarian emergencies, ORISA® is now used in many situations: isolated areas, schools, places affected by natural disasters, or simply households wishing to secure their water supply on a daily basis.

Discover the ORISA® water purifier
De l'eau avec un mauvais goût

📌 See also:

Why does your water taste bad (and what can you do about it)?

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