Apparatus and for providing controlled addition of a first aqueous solution having a first concentration of an aqueous chemical species at a first flow rate to a second aqueous solution having a second flow rate to provide a diluted first solution of a desired selected concentration of the chemical species, the apparatus having a second solution sensor to obtain data on the second solution selected from the second flow rate and the temperature of the second solution; a first solution sensor to obtain data on the temperature of the first solution; a pump to effect addition of the first solution to the second solution to provide the diluted first solution; and a CPU (i) to receive the data selected from the second flow rate and temperature data from the second solution sensor; (ii) to receive the temperature sensing data on the first solution from the first solution sensor; (iii) to effect algorithmic treatment of the data from the first and second sensor, to provide pump control data; and (iv) to control the pump in consequence of the pump control data to effect controlled addition of the first solution to the second solution to provide the diluted first solution of the desired selected concentration of the chemical species. The apparatus is preferably used as part of a full drinking water delivery system which is economic and reliable over the full range of drinking water demands of livestock animals. The most preferred pump is a positive displacement gear pump.