Chloramines & Pool Operation

Encourage healthy swimming to prevent chloramines from forming by stopping pee, poop, urine, dirt, and sweat from entering the water in the first place.

• Post signs or posters in the locker room that encourage swimmers and staff to:
  • NOT enter the water when they have diarrhea,
  • Use the toilet before getting into the water,
  • Wear a bathing cap while in the water, and
  • NOT to pee or poop in the water.
• Require swimmers and staff to at least take a rinse shower before getting into the water—in other words, swimmers and staff should be wet before they get into the water. Even a quick rinse shower removes much of the body waste that helps form chloramines.
• Be on alert for poop in the water; the distinctive chloramine odor in the swimming area; and respiratory, eye, or skin irritation in swimmers and staff in the swimming area.
  • If the swimmer who pooped in the water is identified, charge a fee to the swimmer or parent of the young swimmer for fecal incident clean up[PDF – 4 pages]

Ensure that airflow in the swimming area is set up to minimize the buildup of chloramines in the air.

• Set up the heating, ventilation, and air conditioning (HVAC) system to move fresh air across the water’s surface and towards air exhaust vents to prevent the buildup of chloramines on top of the water’s surface.
• Exhaust air polluted with chloramines from the swimming area to the outside.
• Bring fresh air from the outside into the swimming area. If the fresh air is cold, this will increase heating costs, but the cost of patron discomfort and illness linked to chloramines can be higher.

Monitor combined chlorine (chloramines are a type of combined chlorine) levels in the water and treat the water, especially when levels are too high.

• Calculate the level of combined chlorine.
  1. Measure the amount of total chlorine in the water.
  2. Measure the amount of free chlorine in the water.
  3. Subtract the free chlorine number from the total chlorine number:

combined chlorine = total chlorine – free chlorine

• Get rid of chloramines in the water, especially when the combined chlorine level is too high (for example, more than 0.4 ppm).
  • Superchlorinate to off gas chloramines from the water and start to convert them to nitrogen gas.
    1. Close the pool to swimmers.
    2. Make sure the swimming area is well-ventilated, because superchlorination (also known as “breakpoint chlorination”) causes off gassing of the chloramines and creates nitrogen gas.
    3. Raise the free chlorine level to 10 times the combined chlorine level.
    4. Bring the free chlorine level back down to the required operating range.
  • Break down chloramines in the water, using ultraviolet light or ozone systems, which are also known to kill Cryptosporidium ¹.