[danavuia.1987]

One water treatment plant.
Residual chlorine at the exit is 1.2 mg/l, ammonium is 1 mg/l
At the consumer   tap ( distante of 300 m of water treatment plant):residual chlorine 0, combined chlorine 0, amonium 1.2 mg/l.
Free residual chlorine analyze: 5 drops of ortotoluidine and add 10 ml of water, and in 15 second read the colour
Combined chlorine: read the colour after 5 minutes.
It is right the way i am doing?
Water sample taken at the consumer tap has no  colour( no combined chlorine).
Why?
Sorry for my english.