The level of chlorine existing in the distribution system after chlorination at the drinking water treatment plant. The residual chlorine level will be a function of the level of microorganisms and the potential for additional THM formation in the distribution system.

The amount of measurable chlorine remaining after treating the water with chlorine. The amount of chlorine left in the pool or spa water after the chlorine demand has been satisfied.. SESQUICARBONATE Sodium Sesquicarbonate - A chemical mixture of equal parts of soda ash and sodium bicarbonate used to increase pH and total alkalinity in pool and spa water. It has a pH of 10.1.

The amount of measurable chlorine remaining after treating the water with chlorine. The amount of chlorine left in the pool or spa water after the chlorine demand has been satisfied. Includes hypochlorous acid (HOCl), hypochlorite ion free and total chlorine and all combined chlorine.

chlorine remaining in water or wastewater at the end of a specified contact period as combined or free chlorine. b

Chlorine remaining in treated water after a specified period of contact time to provide protection throughout a distribution system.

Chlorine allowed to remain in a treated water after a specified period of contact time and to provide disinfection protection throughout the distribution system.