After my first few attempts of making water kefir, I decided to spice things up a little, and experiment with other flavors.
You can read about my first few batches here, made with ginger.

My ginger flavored batches were quite nice. I love ginger, so I used quite a bit of ginger for the second brew, and it made the flavor nice and strong. One can never have enough ginger in my opinion, but if you like it a bit milder, usually using a piece of ginger of about 1 cm will be more than enough.

As you can see, I use quite a bit of ginger. This is a 1.5 liter container. If you like it a bit milder, I'd start with just one piece.

Orange Water Kefir - Not for everyone

After a few ginger batches, I decided to try a few fruit flavors, starting with orange.
So for this, I started the brew as usual:
1 cup (250 grams approximately) of sugar stirred into a little bit of warm water, until it dissolves.
Then I add this to approximately 1 liter of cold clean water. The best water is spring water, or filtered water, but please don't use tap water that's chlorinated.
For filtered water you might have to add some minerals. To do this, you can either add a few drops of trace minerals, a pinch of baking soda or a pinch of sea salt.
Only one of those three is needed. Also check the sugar you use, because it might already contain minerals. In that case, you don't have to add anything.
The minerals are for the kefir grains, because they only react to water with minerals. Without minerals, you can hurt the kefir, and get bad batches.

After adding the sugar water mixture to the water, I add the kefir grains, cover the container with a lid or cloth (in cooler areas, this is just fine. Here we have ants, so I use a lid) and let it sit undisturbed for 24 to 48 hours. In my opinion, 48 is ideal.

Tip: If you stir your mixture once the kefir grains are added, don't use metal, because this seems to have influence on the grains.

After the 48 hours, I added the juice of two small oranges. I'm glad I didn't use the peel, which I will go into a bit later...
I then let the mixture sit for another 24 hours and it was done.

The Verdict

Personally, I didn't love the orange flavored kefir. It did ferment quite a bit due to the fruit, so it was good and carbonated. However, the drink tasted just like that: fermented. But some people would probably love it, I just didn't. It wasn't bad, but it wasn't great either.
Maybe the amount of orange juice would make a difference, so try to experiment with that a little.
I might do one with only one orange to see if that makes a difference.

Lime Water Kefir - Mistakes to Prevent

The next batch I tried was one with lime flavor. I made one big mistake:
I used lime juice as well as the peels.

Big, Big mistake.

The peels made it bitter. Really, really bitter. And I mean REALLY bitter.
I can't even begin to describe the bitterness.
I like a little bitter, but a lot of bitter is just not my cup of tea. I can barely stand a pink grapefruit, it's already on the edge to be honest. But this drink was too much for me.
My son drank it, but it wasn't his favorite either.
So if you're not prepared to have the most bitter drink you've ever encountered, don't use peels...

My lime kefir, without the peels

After this, I did another batch with just the lime juice and it came out lovely. I used 2 limes for this recipe, and you could barely even taste the lime. It actually tasted more like honey, which was surprising to me. There is no honey in the concoction at all! Which makes me think about maybe using honey after the first brew next time...(after removing the kefir grains...very important!).

Anyway, I liked this batch, but I would have liked to have a real lime taste to it, so next time, I'll try it with 3 or 4 limes to see how that turns out. I will let you know once I do!

Conclusion:

So even though the last batch turned out quite nice, and tasted of honey, it wasn't what I wanted from it. You could barely even notice any lime flavor to it. I think using either more lime juice from fresh limes, or even the nice lime juice we have here in a bottle, would do the trick.
It's strange to me, because lime has a lot of flavor! So it shows, it needs quite a bit of experimenting to get it right. Either way, it was still a good experience, and next time, I'll know what not to do. No peels, haha!