Hi @Yogesh,
Thank you for your question and welcome to the Bunnings Workshop community, it is fantastic to have you with us.
Unfortunately, I am unaware of a paint that can used for this purpose, so it is unlikely painting the water feature is going to be the answer to restoring it.
If there is mineral build up on the water feature, you might be better off attempting to clean the water feature as opposed to painting it.
If you gently scrub the white areas, does it come off?
The only other option I see is to contact the manufacturer so to ask them for their advice.
Let me know how you go.
Jacob
