What can you add to water to make it hard enough for tea? I was living in southern California where the water is one of the hardest in the country, but once passed through a Brita filter it was perfect for tea.

Now I am living in a country where the water is soft. All the sources of water are surface sources and this has been aggravated by heavy rainfall. The water coming out of the tap and all sources of local bottled water I can find are soft.

As a result, I have not been able to brew tea that has much of any taste. The Darjeelings that I enjoyed in California with their beautiful distinct aroma, here do not taste or smell like anything. Even the strongest teas like double bergamot earl grey have just a faint aroma here. Assam comes out sour.

I have tried the baking soda trick or putting in a pinch of baking soda, which helps a little bit (mostly in color) but not that much and has its own taste. Using too much quickly ruins the tea.

There are few imported waters here and in any case, I don't want the expense of using expensive imported bottled waters. There are also no mineral drops on the market here as far as I know.

So besides baking soda, what are some things I can add to the water to change its mineral profile, pH level and make it suitable for tea?

Would dissolving calcium and magnesium supplements in the water work?

I have heard of Epsom salts being used by brewers for its magnesium content, but don't know if that would work for tea.
You are going to need Epsom salts, baking soda and Calcium chloride to make a run of the mill hard water. You can easily find these in food grade and small quantities at your local homebrewing store. I live in Seattle and we have notoriously soft water, but I don't mind it for my tea. But for brewing, I use these minerals all the time. 


Get 500ml of distilled water
Add half tablespoon of Epsom salts stir until dissolved
Add half a teaspoon of Baking soda stir until dissolved
Add half a teaspoon of calcium chloride until dissolved


Wait a bit until everything dissolves. Voila instant hard water!

If you are really serious, there are plenty of resources out there, especially around the homebrewing community. Here is an online Brewing Water Calculator