What should be be chlorine dose of a water that has a chlorine demand of 2.6 mg/l if a residual of 0.4 mg/l is

Question

What should be be chlorine dose of a water that has a chlorine demand of 2.6 mg/l if a residual of 0.4 mg/l is

Answer 1

You simply add the demand to the desired residual (2.6+0.4) = 3.0 mg/l or ppm  

Some refer to the residual as "free chloride" which is the remainder not consumed by the demand.