Hey Damo
All the different kind of water you gave your plant is killing it. These plants have delicate root systems and can ONLY take distilled water OR rain water.
Tap water has chemicals and minerals that will harm the plant. Most house plants can take this. But carnivorous plants cannot.
The same thing goes for mineral water.
These plants live in very poor soil. Void of mineral, nutrients. That is why they have created the ability to catch bugs. This allows for the plants to obtain the things they cannot get from the soil. Most of these plants don't use their root for anything but to anchor them to the ground ( or tree ). Many gather nothing from the soil. So by putting fertilizer, minerals, and what not damage the roots and will kill the plants.
Having the VFT sit in a tray of water is the best thing to do for it. In the wild, they live in a swamp or bog enviornment. So it is best to emulate that. Just make sure not to have the water in the bowl/saucer higher than the bulb/rhyzome. That will rot the plant. Just having it sit in a 1inch or so of water will not harm it at all.
The best thing you can do right now is to get some distilled water and try to 'flush out the soil' meaning....pour the water around the plant ( never on top of it!! ) and try to get out the stuff that is in the soil.
OR
Even better...if you have canadian sphagnum peat moss ( nothing esle ), I would repot it. Gently pull the plant out of the soil ( not damaging the roots ) and repot. The plant will take a week ( or more) to recover from the transplanting, but it should live.
Hope this all helps
Let us know how your plant does!
jeff