Pool-Water Sanitation

By Joseph Walker

Pool-water sanitation is complex, with several variables to manage to ensure the water is healthy for contact (and unplanned consumption), clear enough to monitor bathers safely, and visually appealing. In its simplest definition, sanitation is typically a chemical that kills germs. In order of importance, a pool-sanitation system includes:

  • Disinfection
  • Circulation
  • Filtration
  • Evacuation.

Almost every pool is initially filled with clean drinking water, whose supply system and quality meet the minimum standards of the

Circulation helps keep disinfection and stabilization chemicals active so they can neutralize or kill potentially harmful intrusions brought into the pool. The water is initially disinfected to a high standard, but the disinfectant capacity of this water must be increased in order to process the billions of additional viruses, bacteria, parasites, pathogenic amoebae, fungi, and algae fungi that will eventually enter the water from the air, insects, pests, and people.

Great pool water begins with disinfection. Clean, potable water is enhanced to prevent recreation water-illnesses without exceeding the chemical tolerance of bathers. Stabilizers, acids, and other chemicals all play a role in balancing the disinfection capacity to reduce corrosion of the circulation system. A UV system functions as a second disinfection strategy as it kills many bacteria through intense light exposure. The UV system requires a circulation component to pull and push the water into and through the light chamber; its overall effectiveness is so high that it helps reduce the need of chemical disinfectants.

Circulation helps keep disinfection and stabilization chemicals active so they can neutralize or kill potentially harmful intrusions brought

Filtration safely collects and contains unwanted debris and trash that enter the pool so they are no longer able to make contact with bathers. The circulation loop makes a UV system function. Circulation with a chemical feeder system (currently required by nearly all health departments) allows the operator to continually replace the chemicals being depleted by the environment (sunlight), and through oxidation, which kills microscopic organics.

Without a mechanical circulation system in place (water pumps), the basic physics of dilution would eventually disperse the chemicals added into the pool water so the entire volume eventually reaches the minimal levels necessary to function as a preventative environment. However, the use of water pumps creates flow and circulation (stirring) within the pool to speed up the process. Without mechanical circulation, it would take days for the chemicals to dilute, and a UV system would be ineffective.

Turnover refers to the time it takes to circulate the volume of water in the pool through the pumps and sanitation stations (skimmers, filters, chemical feeders, and UV). Increased turnover increases the dilution of chemicals, and, if installed, the exposure to UV. Since the typical design of a pool-circulation system causes the water to be continually diluted, multiple turnovers (typically six) are needed to actually process all of the water in the pool.

Filtration safely collects and contains unwanted debris and trash that enter the pool so they are no longer able to make contact with bathers. Many organic and inorganic materials (dirt, leaves, skin cells, hair, lotion, and trash) enter the water by means of people, animals, insects, and the wind. If any of these objects are biologically harmful, it is initially the role of the disinfectant to neutralize them. Though filtration captures harmful organic objects, this is a minor component of the disinfection process but a major part of the sanitation process. On a large scale, pool-water filtration involves staff members picking items out of the water, then skimming/straining smaller objects, and finally filtering at the microscopic level. Each level requires safe capture, proper containment, and proper disposal.

The final step in the sanitation strategy is evacuating or safely removing the waste. Larger debris strained from the water by the staff/skimmers is typically removed using trash cans that are then collected by the sanitation department. To remove smaller particles entrapped by the filtration system, a backwashing strategy of the filter medium into a water-sanitation line is used. Finally, to remove the microscopic, neutralized, organic particle material and silt that do not get circulated into and captured by the filter, technicians vacuum them directly out of the water into the wastewater lines. Using a micron-filtration vacuum system eliminates the need to dump hundreds of gallons of water, but the long-term cost and maintenance of these micron vacuum systems are sometimes greater than the cost of replacing the discarded water with treated drinking water.

Pool-water management requires a comprehensive sanitation strategy that maximizes the effectiveness of the existing disinfectant, circulation, filtration, and evacuation systems. A competent operator balances the performance limitations of the system with the highest level of use-demand allowed. Overloading the ability of the system and compromising patron safety would be management error.

A primary expectation of patrons of all public-pool environments is water safety and clarity. The public expects a water technician to protect the general health of the community. Understanding and maintaining the regulations, policies, components, and effectiveness of the pool-water sanitation process in a facility is paramount to a profitable operation that maintains the public trust.

Joseph Walker is an assistant professor of recreation at the University of North Texas. His recreation background includes aquatics, community/special event programming, facility operations/development, staff management, and comprehensive planning. He can be reached via e-mail at joseph.walker@unt.edu .