How do you get white water stain off a dark brown colored kitchen sink

Try scrubbing that place with Bar Keeper's Friend. It's commonly found at the supermarket with the other cleansers.

You really need to know what your sink is made of. Composite sinks can be etched with using the wrong cleaners. Do you know where you got It? Do you know where they are sold? You may need to get more information so you can call the manufacturer.

Thank you Kelli. That is why I am asking. I don't want to do damage to it. I think I know but I want to confirm it. Ty

It's most likely porcelain/enameled cast iron They made them in brown,avocado green & in harvest gold for kitchens and pink or light green & blue in bathrooms. And of course the standard white.Try to use baking soda and ammonia put ammonia down first then baking soda and scrub with sponge. When you put your dish tub in sink put wash cloth down first this will help to keep finish from getting scratched,making sure it dries between tubfulls so it doesn't stink or get moldy from being damp/wet. Here are a few tips I found online don't know how these work but worth trying https://www.apartmenttherapy.com/how-to-clean-an-old-porcelain-enamel-bathtub-or-sink-137148

Hello Dorothy,

Try using a Lime scale remover. Best wishes