When the pool water smells bad, many people assume that the problem is down to too much chlorine. However, in most cases, the opposite is true: a bad smell is usually a sign that the water needs proper treatment to restore its chemical balance.
As well as being unpleasant for swimmers, a smelly swimming pool may indicate the presence of organic contaminants, filtration problems or imbalances in the water parameters. Identifying the source of the problem is essential in order to apply the correct solution and ensure a safe and comfortable swimming experience.
In this article, we explain the reasons behind a bad smell in the swimming pool and what to do if the pool water smells bad to quickly restore water quality.
Why does the pool water smell bad?
An unpleasant smell in a swimming pool can be caused by a number of factors. Although the smell of ‘chlorine’ is usually the most common, there are other causes that also affect water quality.
Chloramines: the most common cause of unpleasant odours
Chloramines are formed when free chlorine reacts with organic matter present in the water, such as:
- Sweat
- Cosmetic Leftovers
- Sun cream
- Urine
- Leaves and organic waste
These substances generate chemical compounds that produce the characteristic strong odour which many people mistakenly associate with an excess of chlorine.
In fact, a swimming pool that smells strongly of chlorine usually needs more disinfection, not less.
Presence of algae and microorganisms
When disinfectant levels are insufficient, algae, bacteria and other microorganisms can proliferate, causing unpleasant odours.
Some associated symptoms are:
- Turbid water
- Slippery surfaces
- Appearance of green or yellowish spots
- A smell of damp or mould
Problems with the filtration system
The filter is responsible for removing suspended particles and organic matter.
If the filtration system is faulty, contaminants may build up, ultimately affecting water quality and causing unpleasant odours.
The most common problems include:
- Saturated filters
- Insufficient filter cleaning
- Insufficient filtration time
- Poor water circulation
Chemical imbalance in water
Chemical parameters have a direct influence on the effectiveness of treatment products.
An unbalanced pH or incorrect alkalinity can reduce the disinfecting power of chlorine and encourage the development of odours. In this post, we explain how to control the pH in your swimming pool.
What to do if the pool water smells bad
The solution will depend on the cause of the problem, although there are a number of recommended steps for most situations.
Carry out a comprehensive water analysis
The first step is to measure the key parameters:
- pH
- Free chlorine
- Combined chlorine
- Alkalinity
- Stabiliser
A thorough analysis makes it possible to identify the source of the problem and avoid unnecessary treatment.
Carry out a shock chlorination treatment
Where chloramines or high levels of organic contamination are present, shock chlorination is usually the most effective solution.
This treatment enables:
- To oxidise accumulated organic matter.
- Remove chloramines.
- Restoring water’s disinfecting power.
- Improve clarity and odour.
It is advisable to carry this out using the doses specified by the manufacturer and to keep the filtration system running for several hours.
Check and clean the filtration system
A clean filter helps to remove residues that contribute to the development of unpleasant odours.
Recommended maintenance tasks include:
- Backwashing the sand filter.
- Cleaning of filter cartridges.
- Inspection of pumps and skimmers.
- Checking the daily filtration time.
Using complementary treatments
Depending on the problem identified, specific products may be used, such as:
Chloramine removers
They help to remove the compounds responsible for the strong smell of chlorine.
Active oxygen
Active oxygen for swimming pools acts as a supplementary oxidant, improving water quality and reducing odours without producing irritating by-products.
Algaecides
If the unpleasant odour is caused by an algal bloom, an algaecide treatment may help to restore the water’s balance.
Flocculants and clarifiers
They help remove microscopic particles that contribute to a decline in water quality.
How to stop your swimming pool water from smelling bad again
Prevention is always simpler and cheaper than rectifying a problem that has already arisen.
Maintain regular disinfection
Regularly checking the levels of chlorine or disinfectant used is essential to prevent the build-up of contaminants.
Monitoring water balance
Regular checks on:
- pH
- Alkalinity
- Calcium hardness
- Stabiliser
It helps to optimise the effectiveness of chemical treatments.
Improving hygiene for bathers
Simple measures such as showering before going into the pool help to significantly reduce the amount of organic matter entering the pool.
Carry out preventive maintenance
A regular maintenance programme should include:
- Cleaning the bottom and walls.
- Waste extraction.
- Cleaning baskets and skimmers. We’ll show you how to keep your skimmers in perfect condition.
- Inspection of the filtration system.
- Regular water testing.
Signs that you need to act immediately
If you notice any of these symptoms alongside a bad smell, it is advisable to take action as soon as possible:
- Turbid water.
- Irritated eyes after a bath.
- Foam on the surface.
- Presence of algae.
- An intense, lingering aroma.
- Rapid decrease in free chlorine.
These indicators usually point to a decline in water quality that can rapidly worsen.
Conclusion
If the pool water smells bad, it is important to identify the cause before applying any treatment. In most cases, the problem is linked to the formation of chloramines, the build-up of organic matter or a chemical imbalance in the water.
Carrying out regular tests, ensuring proper filtration and using specific water treatment products are key to preventing unpleasant odours and ensuring a clean, safe and comfortable swimming pool. If you’re wondering what to do if your pool water smells bad, a combination of diagnosis, proper disinfection and preventative maintenance will be the best strategy for quickly restoring water quality.
