(monthly exchange of empty bottles for full bottles) When a customer signs up for example 3 x 5 gal High pH they will get 4 x 5 gal bottles High pH on 1st delivery with the chosen cooler. On monthly delivery they will get a full 5 gal bottle for every empty returned up to the 3 per contract, that way they have 1 x 5 gal on the cooler. Should they return 4 empties and require 4 bottles they will get 3 per the Water Club contract and pay normal price for the 4th 5 gal bottle. Cannot get the 20% discount off Water Club as it is already discounted!