Dear Massi,  I am having real issues at work and I wanted to know if there were grounds for me to speak to someone about discrimination.

I have placed a plastic bottle in the toilets several times because I like to wash myself afterwards. But each time it has been moved.

I have explained this to the manager who says it does not matter and having a bottle or a lota in there is not permitted as it is unhygienic. 

I say it is unhygienic not to wash yourself. This is discrimination I think as my religion says I should.
Should I pursue this formally?

Massi says, You have articulated your viewpoint and your concerns to your manager who in turn has explained their reasons for taking the respective action.

Rather than making an issue out of this, try and find a compromise. 

You can use wet wipes which are hygienic as they can then be disposed of. 

If using a plastic bottle is something you cannot give up, then why not bring it in and out of the bathroom with you when required.