How to Assess Pool Water Quality?
The hygiene and safety of swimming pool water is a key link to protect public health, and disinfection is the top priority to ensure hygiene and safety. So, how much do you know about the hygiene of swimming pools? What are the requirements for water quality indicators? And what do these indicators mean? To ensure the safety of swimmers, it is essential to understand the scientific metrics behind water quality and how to interpret them.
Clear Water ≠ Safe Water: Indicators & Meanings
It refers to the content of suspended pollutant particles (such as dust, human grease, algae, etc.) in the water, which directly reflects whether the pool water is clear or turbid and affects swimmers' vision and comfort.
The most important indicator reflecting the acidity and alkalinity of water quality. If the pH is lower than 7.0, the water is acidic, leading to rapid decomposition of disinfectants and increase the consumption of disinfectants; a too high pH will inhibit the efficacy of disinfectants and reduce their disinfection and sterilization effect. Both excessively high and low pH values can cause discomfort to the human body.
Reflects the continuous disinfection capacity of the disinfectant in the pool, and is directly related to the safety of water quality. Scoop a small amount of pool water and smell it – if no chlorine odor is detected, the disinfectant dosage may be insufficient, and the pool water cannot be effectively disinfected; if the odor is pungent, the chlorine content may be excessive, which will irritate the skin and eyes.
It affects the activity of pool water and may cause significant irritation to the skin and mucous membranes; an excessively high concentration can lead to asthma and skin itching.
It controls the release amount of free residual chlorine and affects the content of free residual chlorine that diffuses and adsorbs to the surface of bacteria, thereby influencing the bactericidal effect of chlorine.
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Reflects the degree of microbial contamination of water quality – the higher the value, the more severe the contamination. It can be used to evaluate water cleanliness and assess the effect of purification and disinfection, and combined with the coliform index, it can judge the source of contamination and the safety level.
One of the important microbial indicators reflecting the hygienic quality of water. Coliform bacteria come directly or indirectly from the feces of humans and warm-blooded animals, indicating the pool has been contaminated and the possible presence of pathogenic bacteria in the water.
Simple Methods to Assess Water Quality
You don't always need a laboratory to perform a basic check. Use your senses with these four simple steps:
| Method | Assessment Criteria |
|---|---|
| 1. Look | For swimming pools with white tiles, the water should appear bright light blue. It should be transparent enough to see the bottom clearly, with no floating debris or sediment. |
| 2. Smell | A faint chlorine odor indicates that the residual chlorine content is basically up to standard. A sharp, stinging odor indicates poor water quality or excessive chemical imbalance. |
| 3. Feel | Good quality water feels "soft". If the water causes itchy skin, the quality is likely poor. Additionally, if the bottom tiles feel slimy, algae or biofilm may be present. |
| 4. Stir | Create small ripples or bubbles in the water. In high-quality, well-oxidized water, bubbles should disappear within 10–15 seconds. If they linger, the water pool edges should be cleaned and the floating oil removed, and the oxidation capacity needs improvement by raising the free chlorine level. |
Common Water Quality Problems & Solutions
1. Green Water
Phenomenon: The pool water turns green, the pool walls become slippery, and the water looks like "spinach soup".
Cause: Insufficient disinfection or strong sunlight exposure leads to the rampant reproduction of green algae.
Solution: Add algaecide in time, make up chlorine dosage, install shading facilities and clean algae on the pool wall.
3. Turbid Water
Phenomenon: A large amount of suspended matter, low transparency, unable to see toes when stretching hands into the water, and swimming feels like floating in clouds.
Cause: Possible filter system failure or insufficient disinfection.
Solution: Inspect and clean the filtration system, increase disinfection concentration and fish out suspended solids in the water.
2. Pungent Odor
Phenomenon: A strong "disinfectant odor" hits as soon as you enter the venue, eyes become bloodshot, and the throat feels burning.
Cause: In general, excessive combined chlorine or a too high pH value.
Solution: Measure pH, FC and CC, and adjust pH to the optimal range of 7.2-7.8 and shock.
4. Abnormal pH Value
Phenomenon: A too high pH (>7.8) leads to reduced disinfection effect, scale deposition and dry skin for swimmers; a too low pH (<7.2) corrodes equipment and irritates eyes and mucous membranes.
Cause: The low value of TA leads to frequent changes in pH.
Solution: Monitor TA and raise it to a reasonable level. Measure pH and add acidic regulator if pH is too high, alkaline regulator if too low; test regularly and adjust in small, frequent doses.
