`D` Aquarium water disposal.

Alot of the disease research I am doing for an up coming essay on Mycobacterium leads me to believe that it may be possible for Bacteria infecting a dead fish carcass to survive being flushed and end up in the water supply. For humans it is kinda OK because we disinfect our drinking water. The creatures living in our waterways do not have this protection. Also when we flush aquarium treated water down our drains and toilets there is potential for increased release of bacterium and viri that are resistant to medications.

Waste goes to the treatment plant ,is liquidized,any solids(cotton buds and stuff) removed by a coarse filter and put in a large pond to settle.The semi clean water is drained off and sprayed over a filtration medium,such as gravel or stone chips where bacteria dine on any organic particles (poop).The very near clean water is drained off into the environment at which point it is probably cleaner than the river it goes into
The sludge that remains can be used for agricultural fertilizer or burnt as a fuel substitute.

By flushing things down the toilet, Fish tank water from treated fish, especially chemicals (cosmetics, cleaning supplies and medications) will eventually end up in the water supply. Most water treatment plants are not designed to destroy or even remove these things from the waste water.