Water quality and public health

Water quality and public health

Water temperature and chemistry control, pollution prevention and sanitary management of urban fountains

Water quality is part of the main function of fountain. Improper water can spoil the appearance of the complex, damage the equipment and affect the health of visitors and staff. Therefore, the design and operation of the fountain should simultaneously cover three issues: the appearance quality, the chemical conditions and the microbial status of the water.

Clear water is not necessarily microbially safe. Observing the transparency of the pond or the operation of the pump is also not enough to confirm the performance of the treatment. Evaluation should be based on measuring, cleaning, checking equipment and recording results.

This chapter examines temperature, chlorine, and pH control, algae and biofilm prevention, stagnation management, disinfection, extended shutdowns, closed environments, legionella, and installation site limitations, according to the original index. Values ​​taken from international sources are listed with their range of application; The implementation limits of each project must be adapted to the requirements of the responsible health authority and the water management plan of the same complex.

Prerequisite: specifying the type of use of the fountain

Before setting up the sanitary program, the actual use of the water fountain must be determined.

If people are using a decorative fountain for gaming, the initial title of the project is not enough. The CDC recommends that such a complex be managed like a water play area or that effective measures are taken to prevent people from entering. Manual for using interactive water fountains, CDC ^[219]

32–1. Water temperature control

32-1-1. The importance of temperature

Water temperature affects microbial growth and operating conditions. In a fountain, sunlight, ambient heat, submerged equipment, and the location of the tank can increase the temperature of the water.

The CDC's own guidelines for decorative fountains recommend keeping temperatures below 25 degrees Celsius, and consider the range of 25 to 45 degrees Celsius favorable for Legionella growth. This recommendation does not mean that water below 25 degrees is sterile; Temperature control should be combined with other measures. Legionella control in decorative fountains ^[220]

32-1-2. monitoring method

For the operation form, it is suggested to record the temperature at fixed points and specific times. The selection of points should consider the possibility of warmer water or less flow; For example:

• Storage tank or balance;

• main pond;

• the end of the circuit or an area with poor circulation;

• Location close to heat generating equipment, if related to risk assessment.

Recording the morning temperature alone may not indicate the hot hours of the day. During the setup phase, measuring at several times helps to recognize changes.

3-1-32. Design and operation measures

In the design review, it is possible to evaluate the shadowing of the tank, the reduction of unwanted heat, the installation location of the equipment, and the possibility of temperature measurement.

If the temperature exceeds the project control limit, the cause, duration and status of other controls should be investigated. Automatic increase of the chemical, without a specific agenda, is not an appropriate response to all cases of temperature increase.

32–2. Chlorine and pH control

32-2-1. Separation of terms

In chlorinated circuits, a difference should be made between these cases:

The injected amount cannot be considered equivalent to the remaining amount in the reservoir. Also, recording "chlorine" without specifying the type of measurement makes the report ambiguous.

As the pH increases, the disinfection effect of chlorine decreases; Too low pH can also aggravate corrosion. Therefore, these two indicators should be checked together. CDC Explanation of Chlorine, pH and Water Testing ^[221]

32-2-2. Example of reference limits for an interactive fountain

CDC guidelines for interactive fountains state the following values:

This table does not set the upper limit of chlorine or the license to use a stabilizer. The selection of materials and the concentration ceiling should be adapted to the governing regulations and the product order. These numbers should not be generalized to all decorative fountains and ponds. CDC Guide to Interactive Water Fountains

3-2-32. Measurement quality

For the field test, appropriate tools and reagents, validity date and correct method of use are important. The automatic sensor also requires cleaning, calibration and comparison with an independent measurement.

The CDC introduces the DPD kit for chlorine testing and warns that high concentrations of chlorine may discolor the test and give a falsely low or zero result. Therefore, the unexpected result should be checked with the appropriate measurement range method. Water test guide

32-2-4. Connection of injection with flow

Material injection should be automatically stopped when there is no or lack of circulating current. The command to turn on the pump does not take the place of proving the existence of real flow.

Separate storage of incompatible materials, labeling and access to safety data sheets are also part of this system. Safety of chemicals and injection equipment, CDC ^[222]

32–3. Preventing the formation of algae and biofilm

32-3-1. Difference between algae and biofilm

Algae may appear as discolored water or coatings on surfaces. A biofilm is a community of microorganisms in a layer attached to a surface and is not necessarily green or easily visible.

Sediment, corrosion and organic matter can provide suitable conditions for the establishment of pollution. For this reason, water quality control is not limited to adding disinfectants, and maintenance of surfaces and equipment is also important. Principles of Water Management Program, CDC ^[223]

32-3-2. Suggested places of inspection

In the fountain, the checklist should also include low-visibility areas:

This table is a suggested template for recording the situation and should be completed with the actual map of the complex.

3-3-32. The role of cleaning and anti-algae substances

The control program should coordinate pollutant removal, surface cleaning, treatment service and water chemistry control. The cleaning interval is determined based on the condition of the collection and risk assessment; A fixed distance is not enough for all projects. HSE guidance also bases control of aerosol generating systems on risk assessment, maintenance, decontamination and monitoring. HSE Technical Manual, Part III ^[224]

Anti-algae materials should be used only within the scope of their authorized use. For example, OASE introduces AlGo Fountain Concentrate for fountain care and algae and sediment control; This introduction alone is not sufficient confirmation of disinfection for public contact. OASE fountain care product ^[225]

32–4. Management of stagnant water

32-4-1. Stagnation in Roshan system

The fact that the fountain is turned on does not guarantee that all the water in the collection is properly circulated. An unused branch, under-floor compartment, corner of a tank, or blocked path can have low-flow water.

For circuit review, it is suggested that each branch in the map be marked with one of the states "active", "intermittent use" or "out of use". Then, determine the management method for intermittent and inactive branches.

32-4-2. Separation of display time and purification time

The demo program may be active for a few hours a day, but the water management program should be defined for 24/7.

For decorative fountains, the CDC recommends avoiding prolonged downtime and daily operation. This recommendation is not a license to turn on a suspected contaminated water fountain for a few minutes. CDC's Guide to Decorative Fountains

In the design of the control, it is necessary to separate the "display off, water management active" mode from the "completely out of service" mode. The function of each pump, valve and injection system in these cases must be recorded in the operating instructions.

3-4-32. Compensatory water and water replacement

The introduction of fresh water does not necessarily remove the contamination attached to the surfaces. The water change program should be accompanied by checking the incoming water quality, cleanliness and filtration performance.

To manage consumption, record the volume of compensated water and the reason for consumption: evaporation, spraying, filter washing, scheduled discharge or leakage. This record also makes it easier to detect unusual consumption.

32–5. Periodic disinfection

32-5-1. Three different activities

In the operation agenda, these three activities should be separated:

• Routine disinfection: maintaining control conditions during operation;

• Scheduled cleaning and disinfection: system service at the designated time;

• Specific Corrective Action: Response to contamination, control failure or health incident.

The amount and contact time of the substance in these situations are not the same. "Weekly shock" is not considered a complete health program without clear purpose, water quality and valid prescription.

32-5-2. Agenda content

The specific agenda of each project should specify:

This table is the list of agenda components; Its arrangement is not considered the executive version of disinfection.

Materials should only be used by trained personnel. The mixing of incompatible materials and the use of shared contaminated equipment for the removal of materials should be controlled in the training and design of the storage area. CDC Chemical Safety Guide

3-5-32. Suspected disease event

If there is a possibility that the water fountain is related to the disease, the complex should be taken out of operation and the issue should be coordinated with the health authority. Possible sampling before cleaning should be done under the same coordination so that the evidence of investigation is not lost. Action when there is a possibility of illness related to the fountain

32–6. Long blackout conditions

32-6-1. Select maintenance mode

Seasonal blackout, repairs or closing of the building must have a specific plan. The two possible modes are:

The choice must be made for the actual system. Draining the tank may not remove water remaining in the pump, filter, and pipes; On the other hand, some parts have limitations for long drying.

In the closure file, the status of each department, the date of the last service, consumables, separated equipment and the person responsible for the visit should be recorded.

32-6-2. reopening

After a long pause, turning on the display directly is not a good way to assess readiness. The proposed reopening agenda includes the following steps:

1. Checking the records of the stoppage and the status of the remaining water; 2. Inspection of surfaces, tanks, filters and nozzles; 3. Implementation of cleaning and disinfection according to the assessment; 4. Checking the operation of circulation, injection, sensors and protections; 5. Dehydration and measurement of determined indicators; 6. Conduct supplementary tests if needed; 7. Registering permission to return to operation.

The CDC Building Reopening Guide for water fountains also emphasizes cleanliness, absence of visible biofilm, and measurement of residual disinfectant after dewatering. Guide to reopening after a long shutdown ^[226]

32–7. Fountain management in closed environments

The fountain in the lobby, business center or office space should be evaluated in relation to the presence of people and the facilities of the building.

For design review, it is suggested to document the following:

• The distance and direction of spraying relative to the place of sitting and crossing;

• Connecting the water fountain with the air distribution routes;

• Possibility of increasing water temperature due to equipment and environment;

• Access for cleaning behind the water wall and under the components;

• Effects of humidity on surrounding materials;

• Place of storage of materials and their transportation route;

• The possibility of stopping, unloading and service without public exposure.

Ventilation is not a substitute for water pollution control. A risk assessment must take into account the source of water, the possibility of microbial growth, the release of droplets and the people exposed. Evaluation framework for aerosol generating systems, HSE

In projects where disinfectants are stored and injected, the material space and the engine room should be checked for ventilation and to prevent the material from spreading to the occupied areas. Recommended Requirements for Ventilation and Material Safety, CDC

32–8. Aerosol risk and legionella disease

32-8-1. Exposure route

Aerosol in this discussion refers to tiny water droplets suspended in the air. The CDC states that all decorative fountains produce aerosols; The absence of visible fog is not the reason for the absence of these drops. Exclusive guide to decorative fountains

Legionella is a type of bacteria that can cause Legionnaires' disease, a type of pneumonia. The usual route of infection is breathing contaminated droplets. Most healthy exposed people do not get sick; But older people, people with weakened immune systems, chronic lung disease and a history of smoking are at higher risk. How Legionella Spreads, CDC ^[227]

32-8-2. Control chain

Control should cover three areas:

For this reason, reducing the height of the nozzle or changing the shape of the nozzle alone does not prove the control of the hazard.

3-8-32. Legionella test

The test should have the purpose, sampling location, method, laboratory and action after the result.

Culture and molecular methods are not the same: culture is used to identify live bacteria, while some molecular methods may not distinguish between live and dead bacteria. Their reporting units are also not directly interchangeable.

A negative result of one sample is not a permanent guarantee for the whole system. The CDC emphasizes that test results alone are not predictive of disease, and detection of live Legionella in a decorative fountain should prompt program review and corrective action. Legionella routine test guide ^[228]

32–9. Limitation of installation in medical centers and sensitive places

Dedicated CDC guidance recommends that decorative water fountains not be installed in spaces intended for use by people at higher risk of Legionnaires' disease, such as healthcare facilities. CDC advice on where to install water fountains

This issue should be raised before choosing the architectural form. Adding UV or increasing the disinfectant alone is not the basis for ignoring the installation site limitation.

In hospitals, nursing homes and spaces related to immunocompromised patients, decision-making should be done with the participation of infection control, environmental and facility health officials. CDC infection control guidelines also emphasize avoiding fountain placement near high-risk patient care areas. Water and infection control in medical centers ^[229]

For such spaces, the use of visual elements without circulation and water splashing can be considered in the design phase.

32–10. Water management program and record keeping

The water management plan should have a specific person in charge, circuit map, control points, acceptable limits, corrective actions and effectiveness review method. CDC considers this program to be an ongoing process that should be reviewed as system conditions change. The stages of developing a water management plan ^[230]

The following form is suggested for use in the exploitation file:

Simply recording the number is not enough; Departure from control limits should lead to defined action. It is suggested that the person in charge of stopping operation and the person in charge of confirming reopening be introduced in the program from the beginning.

32–11. Correlation of equipment selection with health program

On the GSO site, mechanical filtration and UV equipment are introduced as parts of fountain treatment. The task of each stage, actual capacity, monitoring method and service schedule should be clarified in the project specification. GSO filtration systems ^[231]

To select and deliver the equipment, it is suggested to answer these questions:

• Are all necessary parts of the circuit subjected to purification and control?

• How is the failure of each stage identified?

• Is it possible to clean and replace parts without destruction?

• How will the water management program continue in the shutdown of the show?

• Which data is displayed and recorded to the operator?

Commercial specifications such as "clarifier", "anti-algae" or "UV" must be supplemented with performance evidence in actual use. The responsibility for sanitary operation does not end with the purchase of equipment.

32–12. Suggested images for the book

Educational pictures of pollution and the path of diffusion should be marked with the label "schematic". For archival photos, include the name of the project and the activity stage; The image of clear water or the clean appearance of the equipment should not be presented as a certificate of water health.