Combining education and experience to address combined chlorine

What are organic chloramines?

Organic chloramines have been identified as negatively affecting the pool water and surrounding air. The most common organic chloramines come from urea, found in urine and other bodily fluids. Free chlorine will break urea’s nitrogen to hydrogen (N-H) bond and form a nitrogen to chlorine (N-Cl) bond, similar to free chlorine’s reaction with ammonia.

Free chlorine

NH₂-CO-NH_{2       >}       Cl-NH-CO-NH₂

     Urea                            Monochlorourea

The difference between ammonia and urea’s chemical reaction to free chlorine is based on urea’s unique structure. It has nitrogen to carbon (N-C) bonds, while ammonia only has nitrogen to hydrogen (N-H) bonds. The N-C bond takes days or even weeks to breakdown, depending on the free chlorine concentration. Consequently, urea breaks down more slowly, producing ammonia at low levels over time. The subsequent chlorination of ammonia produces trichloramine, which irritates swimmers’ eyes and membranes and evaporates to create an offensive odour in the area nearby.

The hypothesis that organic chloramines contribute to the presence of combined chlorine in air and water has been substantiated by National Swimming Pool Foundation (NSPF)-funded research, which is published in scholarly journals and presented at the World Aquatic Health™ Conference (WAHC). In fact, the recent WAHC held in Denver, Colo., included a full-day Advanced Chemistry track led by Purdue University professor Ernest ‘Chip’ Blatchley III, Ph.D., PE, BCEE, F. ASCE, which included sessions on chemistry related to organic chloramines, chlorine, and ultraviolet light (UV).

Addressing organic chloramines

Education leading toward prevention of organic chloramines is the ultimate goal. Although perspiration cannot be prevented, water contamination from perspiration, skin cells, and cosmetics can be reduced by showering before entering the water. With urine being the primary source of urea in pools, collaborative consumer education can continue to prevent pee in the pool.

In addition to prevention, water replacement guarantees the reduction of contaminants; however, this solution is not the most environmentally friendly means to reducing and eliminating chloramines. Even partial water replacement is part of European DIN (Deutsches Institut für Normung) standards, the German national organization for standardization. Other oxidization systems, such as UV, ozone, or monopersulfate, also provide benefits.