Let's ignore the safety aspect here, and focus on the 'if i bathe the jug in water so that all the antimony can leach into the water and wash the jug one more time, can all the antimony be removed that way'. In short, no.
There have been a number of studies on antimony in PET bottles. They look at various factors that influence the rate of leaching of Sb from PET bottles. These factors include temperature, UV, colour of bottle, pH, bottle volume and time. There is evidence that leaching is still occurring well beyond 6 months. One study suggests that leaching levels out after about 800 days. Another study calculates that the total levels of Sb in the plastic are very unlikely to be completely leached out.
Factors that have significant influence of amount of Sb leached include:
- time stored (major influence)
- temperature (higher temps have major influence)
- volume of bottle (smaller volume bottles have higher SA/vol ratio and increase leaching)
- type/origin of PET (significant differences between the colour of bottles used in one study)
I'm not aware of a study that attempts to find the conditions whereby Sb no longer leaches into the water, but effectively you would need to bathe the the bottle at high temperature for several days at a time, repeatedly, over months. That's just not going to happen.
Some useful references for you include: