Chlorination (Sodium hypochlorite solution) Sodium hypochlorite is available as a solution in concentrations of 5 to 15 percent chlorine, but is more expensive than chlorine gas (as available chlorine).
ADVANTAGES
Sodium hypochlorite is easier to handle than gaseous chlorine or calcium hypochlorite.
LIMITATIONS
Sodium hypochlorite is very corrosive and should be stored with care and kept away from equipment that can be damaged by corrosion. Hypochlorite solutions decompose and should not be stored for more than one month. It must be stored in a cool, dark, dry area.
PROCESS
Sodium hypochlorite solution is diluted with water in a mixing/holding tank. The diluted solution is injected by a chemical pump into the water supply pipe at a 
controlled rate. Adequate mixing and contact time must be provided.
EQUIPMENT
A basic liquid chlorination system, or hypochlorinator, includes two metering pumps (one serving as standby), a solution tank, a diffuser (to inject the solution into the water), and tubing.
CHEMICALS
Sodium hypochlorite solution is readily available. Sodium hypochlorite can also be generated onsite by electrolysis of sodium chloride solution in specialized proprietary equipment. The only supplies required are common salt and electricity. Hydrogen is given off as a by-product and must be safely dispersed.
