Hard to tell but red is definitely the tap water in.
The sequence goes, sediment, carbon, RO membrane, DI filter.
The waste is the one with the small white piece inline with something like 500mL stamped on it.

You can improve the performance tremendously if you take the horizontal DI chamber off the top and mount it vertically like the other canistersand so that it fills from the bottom and drains from the top. Horizontals are extremely poor performers since they short circuit or channel and not all resin and ater come into contact with each other.