I have a Bunn OHV hot water machine at my house to make my pour over coffee every morning. My Aurelia is on a water softener but this I just pour water from the tap and since it is well water it is fairly hard.

I have notice that there is a ring of lime/calcium buildup around the lid where I pour the water in and once I get it to the Caribbean I will have it set up so I can use softened water, but for now this is what I have.

How can I clean the scale from the inside of this. What chemicals or natural things would work without ruining it for human consumption or changing the taste of the water?

Thanks
Barry