one embodiment the tee fitting can include an open first end 51 an open second end 52 and a middle opening 53 the middle opening 53 can be removably secured to the second end 42 of the second member 40 via a connector such as the illustrated threaded elements 42 a and 53 a for example the first end of the tee fitting 51 can be removably secured to the threaded end 5 a of a conventional shower head assembly 5 via a connector such as the illustrated threaded elements 51 a for example an aerator 60 can be secured within or connected to the second end 52 of the tee fitting 50 and can function to reduce the flow and or pressure of water entering the fitting so as to allow the liquid agent to be introduced to the water flowing through the tee fitting as shown one end of the aerator 61 can be removably secured to the threaded end 1 a of a conventional building shower arm 1 via a connector such as the illustrated threaded elements 61 a for example as described herein each of the tank 12 the first tubular member 20 the valve 30 the.