The Importance of Water Testing in Spa Pools: Keeping it Safe and Clean

The Importance of Water Testing in Spa Pools: Keeping it Safe and Clean

Regular water testing is a cornerstone of safe spa pool ownership. It’s not enough to simply add chemicals; you need to monitor the water quality to ensure that your spa is not only clean but also safe for use. This post will guide you through the significance of water testing, the parameters to monitor, and the actions to take based on the results, all informed by the HSE’s guidelines.

Why is water testing so important?

Spa pools are prone to microbial growth if the water chemistry is not properly maintained [2]. Bathers introduce organic matter that acts as nutrients, and the warm temperatures can promote the growth of bacteria [4]. The testing regime will give you an idea of what contaminants may be present, and how the chemical treatments are working [23, 24]. Regular water testing helps identify and correct imbalances, ensuring the disinfection is effective and preventing the spread of infections like Legionnaires’ disease [14, 15, 37].

Key water parameters to monitor

Several parameters need to be tested regularly to ensure your spa pool is safe and healthy. These can be broadly categorised into chemical and microbiological tests:

Chemical tests

• pH Level: The pH level should be maintained between 7.0 and 7.6. If the levels are too low, the water is acidic which can corrode the spa pool equipment, and too high can lead to scaling and make the disinfection less effective [24, 26].
• Disinfectant Levels: Monitor the levels of your chosen disinfectant, either chlorine or bromine. Chlorine should be between 3-5 mg/l and bromine between 4-6 mg/l at pH 7 [24]. Regular testing ensures the levels are sufficient to kill bacteria and other pathogens.
• Combined Chlorine: Ideal combined chlorine is 0 mg/l, with anything less than 1 mg/l considered acceptable. High levels can cause irritation [24].
• Total Dissolved Solids (TDS): TDS should not be more than 1000 mg/l higher than the incoming water. High TDS can indicate the need for a water change and can lead to corrosion [38, 39].

Microbiological tests

• Aerobic Colony Count (ACC): A count of the total bacteria in the water [40].
• Coliforms and E. coli: The presence of these bacteria indicates faecal contamination and a failure in water treatment [12, 41, 42].
• Pseudomonas aeruginosa: A bacterium that can cause folliculitis (skin rash) and indicates a failure in water treatment [12, 15].
• Legionella: The bacteria that causes Legionnaires’ disease [12]. Testing should be done quarterly as a minimum.

How often should you test?

• Daily: Check the water clarity, and check chemical levels of pH, disinfectant and TDS [27, 43].
• Monthly: Microbiological testing for ACC, coliforms, E. coli and P. aeruginosa should be carried out monthly [11, 12].
• Quarterly: Microbiological testing for legionella is recommended [11, 12].

More frequent testing may be needed depending on the risk assessment for the pool and for its bather load [11, 12, 22].

What actions should you take after testing?

After testing, you’ll need to take action based on the results.

• If pH is out of range: Close the spa pool and check the dosing units. Refill if necessary [17, 44].
• If disinfectant levels are low: Check the dosing units and shock dose if necessary. [44, 45].
• If disinfectant levels are high: Partially replace the spa pool water [45].
• If combined chlorine is high: Review your control measures, and partially replace the water [45].
• If TDS is too high: Review control measures and replace the water [46].
• If E. coli, P. aeruginosa are present: Close the spa pool, carry out a full clean and shock dose if necessary. Check filtration system [16, 17].
• If Legionella is present: Follow HSE guidance for different levels of legionella (see Table 4 in the document). At levels greater than 1000 cfu/l, immediate closure is necessary [47, 48].

Final thoughts

Water testing isn’t optional; it’s a critical aspect of spa pool ownership. Regular testing and prompt action based on the results will protect your health and the health of your family and guests. By staying proactive, you can ensure your spa remains a safe and enjoyable place to relax. Keep visiting thepoolcleaners.co.uk for more on how to maintain your pool and spa.

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