Ozone, with its highly efficient broad-spectrum sterilization, water purification capabilities, core advantages of no harmful disinfection by-products, and improved swimming experience, has become the mainstream high-end water treatment technology in the swimming pool water treatment field. It is widely used in various swimming pool scenarios, including competitive swimming pools, commercial public pools, private residential pools, water parks, and family-friendly toddler pools. It is the core technical solution to ensure swimming pool water safety, enhance swimming experience, and promote the green upgrading of the swimming pool water treatment industry.
Core Mechanisms of Ozone in Swimming Pool Water Treatment
The application value of ozone in swimming pool water treatment mainly relies on its strong oxidation properties. Through three core reaction pathways, it simultaneously achieves three core functions: sterilization, water purification, and disinfection by-product control, accurately solving the industry pain points of traditional swimming pool water treatment.
Broad-Spectrum Sterilization and Disinfection Mechanism
Ozone has an oxidation-reduction potential (ORP) of 2.07 V, with a sterilization capacity far exceeding that of traditional chlorine-based agents.
It can quickly damage the cell membrane and nucleic acid structure of bacteria, viruses, and fungi, achieving irreversible inactivation of microorganisms.
It has an inactivation efficiency of over 99.99% against common pathogenic bacteria in pool water, such as Escherichia coli, Staphylococcus aureus, Legionella, and Pseudomonas aeruginosa.
It can efficiently kill chlorine-resistant pathogenic microorganisms such as Cryptosporidium and Giardia lamblia, which are difficult to inactivate with traditional chlorine-based agents.
These chlorine-resistant pathogens are the main cause of waterborne infectious diseases in swimming pools. Conventional chlorine disinfection requires extremely high concentrations and ultra-long contact time to take effect, while ozone can complete inactivation within minutes.
The sterilization process is non-selective, and it is not easy for microorganisms to develop drug resistance, with stable and reliable effects.
Water Purification and Pollutant Degradation Mechanism
Pollutants in swimming pool water mainly come from sweat, sebum, urine, cosmetics, sunscreen brought in by swimmers, as well as dust and fallen leaves from the environment.
These pollutants can cause turbid water and increased color, and also become precursors of disinfection by-products.
Through oxidation reactions, ozone can decompose soluble organic matter in water and damage the molecular structure of macromolecular pollutants.
It can destroy the stability of colloidal particles in water, promote flocculation and sedimentation, and improve the treatment efficiency of the filtration system.
It can greatly improve water transparency, keeping the pool water with a clear and bright blue appearance.
It can efficiently decompose chloramine substances in swimming pool water.
Chloramines are by-products of traditional chlorine disinfection, and the core culprit of the pungent pool odor and irritation to swimmers’ eyes, skin, and respiratory tract.
By decomposing chloramines, ozone can fundamentally eliminate pool odor and greatly reduce water irritation.
Disinfection By-Product Control Mechanism
Traditional swimming pool water treatment uses chlorine-based agents as the core disinfection method. Chlorine reacts with organic matter and urea in water to generate disinfection by-products such as trihalomethanes (THMs), haloacetic acids (HAAs), and haloacetonitriles.
These by-products have carcinogenic and teratogenic risks. Long-term exposure will harm human health, and are also the core pain point of swimming pool water quality management and control.
Ozone can oxidize and decompose precursors of disinfection by-products in advance, greatly reducing the generation of by-products in subsequent chlorine disinfection.
Relevant data shows that in swimming pools equipped with ozone treatment, the content of trihalomethanes in water can be reduced by 60%-90%.
At the same time, ozone can greatly reduce the dosage of chlorine-based agents, reducing the generation basis of by-products from the source.
The final decomposition product of ozone is oxygen, which will not generate any harmful residues in the water body.
Core Advantages of Ozone Pool Water Treatment Over Traditional Processes
More Thorough Sterilization, Higher Water Safety Level
Ozone can cover chlorine-resistant pathogens that cannot be killed by traditional chlorine-based agents, filling the core prevention and control gap of swimming pool water safety.
The sterilization reaction speed is far faster than that of chlorine-based agents. Ozone inactivates pathogenic bacteria 600-3000 times faster than chlorine, and can complete sterilization quickly in the circulating water treatment link, greatly reducing the microbial risk of the water body.
It can simultaneously achieve multiple effects of sterilization, pollutant degradation, and chloramine decomposition, comprehensively improving the safety of swimming pool water quality.
It meets the high-standard requirements for swimming pool water quality set by the Fédération Internationale de Natation (FINA) and the World Health Organization (WHO), and is the standard water treatment technology for top international competitive swimming venues.
Better Swimming Experience, Stronger Health Friendliness
Ozone can completely decompose chloramines, eliminate the pungent disinfectant odor of swimming pools, and avoid problems such as dry hair, itchy skin, and red and swollen eyes after swimming.
It greatly reduces the dosage of chlorine-based agents, reduces the irritation of chlorine to swimmers’ respiratory tract, skin and hair, and also avoids the oxidative aging of swimsuits and swimming equipment.
It improves the transparency and cleanliness of the water body, and optimizes the visual and sensory experience of swimming.
It is especially suitable for scenarios with high requirements for low irritation and high safety, such as family-friendly toddler pools, infant swimming pools, and hydrotherapy pools.
More Controllable Operation and Management, Better Comprehensive Cost
Ozone can be produced on-site and used immediately, without the need to purchase, transport, and store a large number of chlorine-based agents, avoiding the safety risks and management costs of hazardous chemical management.
It can greatly reduce the dosage of chlorine-based agents, water quality regulators, and flocculants, and reduce daily expenditure on pharmaceutical consumables.
It can extend the backwashing cycle of filtration equipment, reduce the amount of backwashing water, lower the overall water change frequency of the swimming pool, and achieve water and energy saving.
Although the upfront equipment investment of the ozone system is higher than that of the traditional chlorine process, the comprehensive cost of long-term operation is more advantageous, and it greatly reduces the risk of rework due to substandard water quality.
Stronger Environmental Friendliness, Meeting Green Development Requirements
Ozone treatment can greatly reduce the discharge of chlorine-containing wastewater from swimming pools, and reduce the pollution of disinfection by-products to the surrounding water environment.
The decomposition product of ozone is oxygen, with no toxic and harmful residues, and will not cause secondary pollution to the water body and the environment.
It is in line with the current green and low-carbon development direction of the cultural tourism and sports industries, and is the core technical support for the construction of green swimming pools.
Mainstream Processes and Core Application Scenarios of Ozone Water Treatment for Swimming Pools
Mainstream Process Types of Ozone Water Treatment for Swimming Pools
The ozone water treatment process for swimming pools must strictly follow the core process of “ozone dosing – contact reaction – ozone removal – secondary disinfection”, and it is strictly prohibited for ozone to directly enter the swimming pool water body. According to the pool scale, water quality standards, and application scenarios, the mainstream processes are divided into two categories: full-flow ozone treatment process and side-stream ozone treatment process.
Full-Flow Ozone Treatment Process
This process performs ozone treatment on 100% of the circulating water volume of the swimming pool, and is the preferred process for high-standard swimming pools.
Core process flow: pool return water → circulation water pump → sand filtration/precision filtration → ozone dosing system → negative pressure gas-liquid mixing device → ozone contact reaction tank → ozone removal device → activated carbon filtration → secondary disinfection dosing → pool water inlet.
Core process requirements: the contact reaction time between ozone and water is not less than 2 minutes to ensure full reaction and decomposition of ozone, and an efficient ozone removal device is equipped to ensure that the ozone residual in the water entering the pool is ≤0.05 mg/L.
Advantages: stable water treatment effect, high water cleanliness, optimal sterilization and pollutant degradation effect, which can fully meet the high-standard water quality requirements of competitive swimming pools and medical swimming pools.
Applicable scenarios: international/national competitive swimming venues, high-end commercial swimming pools, medical rehabilitation swimming pools, high-standard family-friendly pools.
Side-Stream Ozone Treatment Process
This process performs ozone treatment on 25%-50% of the circulating water volume of the swimming pool, and the rest of the circulating water directly enters the subsequent treatment link. It is the most widely used popular process at present.
Core process flow: pool return water → circulation water pump → sand filtration → branch circuit (ozone dosing – contact reaction – ozone removal) → mixing with main circuit water → secondary disinfection dosing → pool water inlet.
Advantages: lower upfront equipment investment, more controllable operating energy consumption, lower operation and maintenance difficulty, and can be upgraded on the basis of the traditional chlorine treatment process, with low transformation cost and fast implementation.
It can meet the water quality requirements of most commercial pools and private pools, greatly improve water quality, and reduce the dosage of chlorine-based agents.
Applicable scenarios: mid-range commercial swimming pools, fitness club pools, private residential pools, small and medium-sized water parks, hot spring hydrotherapy pools.
Core Supporting Processes and Key Requirements
Ozone has no continuous disinfection capacity and cannot maintain a long-term bacteriostatic effect in the pool water.
Therefore, all pool ozone treatment processes must be equipped with a low-dose secondary disinfection process, usually using chlorine-based agents, to maintain the free chlorine residual in the pool water at 0.3-0.5 mg/L, which is much lower than the dosage of about 1.0 mg/L in the traditional process.
The supporting ozone removal process is the core link to ensure the safety of pool use. The mainstream methods include activated carbon adsorption decomposition, aeration removal, and ultraviolet decomposition, to ensure that the ozone residual in the effluent meets the standard.
For the off-gas treatment process, the ozone off-gas that is not dissolved in water in the ozone system must be equipped with an off-gas destruction device. The ozone in the off-gas is decomposed into oxygen before discharge through catalytic decomposition, activated carbon adsorption and other methods. Direct discharge to cause ozone leakage is strictly prohibited.
Core Application Scenarios of Ozone Swimming Pool Water Treatment
Competitive Swimming Venues
FINA clearly recommends the use of ozone water treatment technology for competitive swimming pools, and top event swimming pools all adopt the full-flow ozone treatment process.
It can ensure stable water quality under high passenger flow load during the event, completely kill chlorine-resistant pathogens, and eliminate the risk of waterborne infectious diseases.
It greatly reduces the content of disinfection by-products, eliminates water irritation, and protects the competitive state and physical health of athletes.
It can maintain extremely high transparency of the water body, meeting the visual requirements of event broadcasting and referee judgment.
Commercial Public Swimming Pools
Including fitness club pools, hotel pools, and public cultural and sports venue pools, they are the most widely used scenarios for ozone technology.
It can solve the pain points of traditional chlorine processes such as strong odor, high irritation, and easy turbidity of water quality, and improve user experience and venue competitiveness.
It reduces the procurement and management costs of chlorine-based agents, simplifies daily water quality operation and maintenance work, and reduces complaints about substandard water quality.
The side-stream ozone process can meet the water quality requirements, with controllable transformation cost and short investment return cycle.
Private Residential Pools
Private pools have high requirements for water safety, low irritation, and convenient operation and maintenance. Small ozone systems have become the standard configuration of high-end private pools.
It can greatly reduce the dosage of chlorine-based agents, avoid skin and eye irritation problems after family swimming, and is especially suitable for families with the elderly and children.
The small integrated ozone equipment is easy to install and maintain, and can operate synchronously with the pool circulation system to maintain long-term stable and clean water quality.
It reduces the frequency of pool water change and cleaning, and lowers the daily operation and maintenance workload of private pools.
Water Parks and Family-Friendly Pools
Water parks are characterized by large water volume, large fluctuation of passenger flow load, and high proportion of children. Water safety and low irritation are the core demands.
Ozone can quickly respond to the pollutant impact caused by the peak passenger flow, efficiently degrade various pollutants brought in by the human body, decompose chloramines, and eliminate odor and irritation.
It can greatly reduce the generation of disinfection by-products, ensure the safety of sensitive groups such as children, and reduce parents’ concerns about disinfectant irritation.
The supporting side-stream ozone process can balance the treatment effect and operating cost, and adapt to the large water volume treatment demand of water parks.
Hot Spring Hydrotherapy Pools and SPA Pools
The water temperature of hot spring hydrotherapy pools is high, which is easy to breed microorganisms. At the same time, the concentration of human secretions is high. Traditional chlorine disinfection is easy to generate a large number of disinfection by-products with strong irritation.
Ozone can maintain a stable sterilization effect in high temperature environment, efficiently degrade pollutants, decompose chloramines, and eliminate water odor and irritation.
It can reduce the impact of chlorine on minerals in hot spring water, retain the health preservation properties of hot springs, and improve the hydrotherapy experience.
Key Parameters and Operation Specifications of Ozone Water Treatment for Swimming Pools
Core Operating Parameter Control
The effect and safety of ozone water treatment depend on the precise control of parameters. All parameters must meet the relevant requirements of Water Quality Standard for Swimming Pools (CJ/T 244-2016) and Hygienic Standard for Swimming Places (GB 9667-2024).
- Ozone Dosage It should be set according to the pool type, passenger flow load, and circulation cycle. The core reference standards are as follows: Private residential pools: 0.3-0.6 mg/L Commercial public pools: 0.5-1.0 mg/L Competitive pools, high-load pools: 1.0-1.5 mg/L Family-friendly pools, hydrotherapy pools: 0.4-0.8 mg/L Excessive dosing is strictly prohibited to avoid the risk of excessive ozone residual and by-product generation.
- Contact Reaction Time The effective contact reaction time between ozone and water shall not be less than 2 minutes as required by the national standard. The full-flow process is recommended to be controlled at 2-4 minutes to ensure that ozone fully completes the sterilization and pollutant degradation reactions. The contact reaction tank must be equipped with a flow guide structure to avoid short flow and ensure the efficiency of contact reaction.
- Ozone Residual Control The ozone residual in the swimming pool water must be strictly controlled at ≤0.05 mg/L. The ozone concentration in the air of the working area around the swimming pool must meet the occupational health standards, with an 8-hour weighted average concentration ≤0.1 mg/m³ and a short-term exposure concentration ≤0.3 mg/m³. It must be equipped with online ozone concentration monitoring equipment to monitor the ozone concentration in water and air in real time, and link system adjustment and emergency disposal.
- Supporting Water Quality Parameter Control The pH value of the pool water should be stably controlled at 7.2-7.8. Within this range, both ozone oxidation efficiency and chlorine disinfection efficiency are in the optimal range. For the free chlorine control of supporting secondary disinfection, the free chlorine residual in the pool water of public pools is controlled at 0.3-0.5 mg/L, and for private pools and children’s pools, it can be controlled at 0.2-0.4 mg/L, which is much lower than the requirements of traditional processes.
System Operation and Maintenance Specifications
- Start-Stop Operation Specifications Ozone system startup sequence: first turn on the circulation water pump, filtration system, off-gas destruction device, and ventilation system, then turn on the ozone generator. Ozone system shutdown sequence: first turn off the ozone generator, keep the circulation water pump, ventilation system, and off-gas destruction device running for more than 30 minutes to ensure that the residual ozone in the system is completely decomposed, then shut down other equipment. It is strictly prohibited to turn on the ozone generator without water circulation and ventilation, to avoid safety risks caused by excessive ozone concentration.
- Daily Operation and Maintenance Specifications Check the operating status of the ozone generator, concentration monitoring equipment data, and air tightness of the dosing system every day, and record the operating parameters and water quality data. Check the operating status of the contact reaction tank, ozone removal device, and off-gas destruction device every week to check for leakage risks. Replace or clean the ozone generation unit and gas-liquid mixing device every 3-6 months, calibrate the online monitoring instruments, to ensure the accuracy of the equipment and stable operation. The activated carbon filter material should be replaced regularly, usually the replacement cycle is 12-18 months, to avoid incomplete ozone removal caused by saturated and invalid filter material. Regularly test the microbial indicators and disinfection by-product content of the pool water, verify the ozone treatment effect, and optimize the operating parameters.
Core Requirements for Safety Control
The ozone equipment room must maintain good ventilation, equipped with explosion-proof ventilation equipment, with a ventilation rate of no less than 12 times per hour.
The equipment room and pool equipment room must be installed with an ozone leakage alarm device, with the alarm threshold set at 0.1 mg/m³. The alarm device must be linked with the emergency shutdown and ventilation system.
It must be equipped with a qualified off-gas destruction device to ensure that the undissolved ozone off-gas is completely decomposed before discharge. Direct discharge to indoor or atmosphere is strictly prohibited.
Operators must receive professional training, be familiar with the operation specifications, safety risks and emergency disposal procedures of the ozone system, and unlicensed and illegal operation is strictly prohibited.
The equipment room must be equipped with personal protective equipment, such as gas masks and goggles, formulate an emergency disposal plan for ozone leakage, and carry out emergency drills regularly.
Existing Bottlenecks and Precautions for Ozone Application in Swimming Pools
Existing Technical and Application Bottlenecks
- High Upfront Investment Threshold The upfront equipment investment of the ozone system is significantly higher than that of the traditional chlorine disinfection process, which has certain obstacles to popularization for small swimming pools and venues with limited budgets.
- Higher Professional Requirements for Operation and Maintenance The ozone system involves multiple links such as electrical, gas-liquid mixing, oxidation reaction, and safety monitoring, which has higher requirements for the professional ability of operation and maintenance personnel than traditional processes. Small and medium-sized venues lack professional operation and maintenance personnel, which is prone to poor effect or safety risks caused by improper operation.
- No Continuous Disinfection Capacity Ozone decomposes rapidly in water and cannot maintain a long-term bacteriostatic effect. It must be equipped with a secondary disinfection process and cannot completely replace chlorine-based agents. Some users have cognitive misunderstandings, which are prone to microbial exceeding the standard caused by canceling secondary disinfection.
- Great Difficulty in Dynamic Regulation in High-Load Scenarios During holidays and events, the number of swimmers in the pool increases sharply, and the pollutant load of the water body fluctuates greatly. The conventional ozone system with fixed dosage is difficult to quickly adapt to the load change, which is prone to water quality fluctuation.
Core Application Precautions
- It is Strictly Prohibited to Dose Ozone Directly into the Pool Water All ozone dosing must be completed in the bypass treatment link of the circulating water. After full reaction and ozone removal, the treated water is sent into the swimming pool. Direct dosing of ozone into the swimming pool will lead to excessive ozone residual in the water body, irritate the respiratory tract and eyes of swimmers, and cause excessive ozone concentration in the air, leading to safety accidents.
- Do Not Completely Cancel the Secondary Disinfection Process It must be equipped with low-dose chlorine-based agents or other long-term disinfection processes to maintain the continuous bacteriostatic capacity of the pool water and avoid the growth of microorganisms in the water body and substandard water quality. The dosage of secondary disinfection can be greatly reduced according to the ozone treatment effect, and there is no need to dose according to the dosage of the traditional process.
- Strictly Control Water Quality Fluctuation and Load Impact Before the peak passenger flow, the ozone dosage can be increased in advance to strengthen the water treatment effect and cope with the pollutant impact. Clean the pool body and filtration system regularly to reduce the accumulation of pollutants, lower the ozone treatment load, and ensure the stability of the treatment effect.
- Avoid the Risk of By-Product Generation For seawater pools and water sources with high bromide ion content, ozone oxidation is easy to generate harmful by-products such as bromate. It is necessary to strictly control the ozone dosage, optimize the reaction conditions, and support bromate prevention and control measures. It is strictly prohibited to excessively dose ozone in water with high organic load and high urea content to avoid the generation of harmful oxidation by-products.
- Do a Good Job in Regular Maintenance of Equipment and Systems Ozone generation equipment, concentration monitoring instruments, and off-gas destruction devices must be regularly calibrated and maintained to avoid ozone leakage and treatment effect failure caused by equipment failure. In particular, it is necessary to focus on checking the air tightness of gas circuits and pipelines to eliminate the risk of ozone leakage.
Industry Development Trend of Ozone Water Treatment Technology for Swimming Pools
With the improvement of national health awareness, the demand for swimming fitness and parent-child water play continues to grow. Consumers’ requirements for swimming pool water safety, low irritation, and high experience are constantly improving, which promotes the continuous upgrading of ozone water treatment technology. The industry development presents the following core trends.
Upgrading of Low-Energy Consumption and Miniaturized Equipment. The industry is accelerating the research and development of low-energy consumption and high-efficiency ozone generators, reducing the power consumption and equipment cost of ozone production, and improving the popularity of small and medium-sized pools and private pools. For private pools and small hydrotherapy pools, we will develop integrated, miniaturized and intelligent ozone water treatment equipment to simplify installation and operation and maintenance, and lower the threshold for use.
Popularization of Intelligent Precision Control System. Combined with online water quality monitoring sensors, the Internet of Things, and AI algorithms, we will develop an intelligent ozone dosing system. It can dynamically adjust the ozone dosage in real time according to the real-time changes of pool passenger flow load, water ORP, residual chlorine, and pollutant concentration. On the premise of ensuring that the water quality meets the standard, it can minimize the operating energy consumption and avoid the risk of excessive ozone dosing. It can realize remote monitoring, fault early warning, and automatic operation and maintenance, greatly reducing the professional requirements for on-site operation and maintenance personnel, and solving the operation and maintenance pain points of small and medium-sized venues.
Optimization of Multi-Technology Collaborative Coupling Process. Promote the in-depth coupling of ozone with ultraviolet, photocatalysis, activated carbon, membrane filtration and other technologies to build a collaborative water treatment system. For example, the ozone + ultraviolet combined process can further enhance the sterilization effect, and at the same time decompose ozone residues and disinfection by-products, further improving water quality safety. The combined process of ozone + activated carbon + ultrafiltration can achieve deep removal of pollutants and meet the extreme water quality requirements of medical pools and high-end private pools. Multi-technology collaboration can further reduce ozone dosage, reduce operating costs, and broaden application scenarios.
Continuous Improvement of Industry Standards and Application Specifications. With the popularization of ozone technology in the swimming pool field, the relevant application specifications, equipment standards, and design specifications will continue to be improved, promoting the standardized application of the industry. The health supervision department’s requirements for the control of disinfection by-products and chlorine-resistant pathogens in swimming pools continue to tighten, which will further promote the popularization of ozone technology from high-end venues to ordinary public pools and community pools.
The Concept of Healthy Swimming Pool Promotes Application Popularization. Consumers’ demand for “odor-free, low-irritation, high-safety” healthy swimming pools has become the core competitive point of the swimming pool industry. As the core solution for healthy swimming pool water treatment, ozone technology will gradually become the standard configuration technology for new swimming pools, and at the same time promote the upgrading of ozone technology for a large number of existing traditional swimming pools, and the industry application space continues to expand.
