I don’t know exactly what you mean by water colored ink…
However. The lighter colors definitely fade, in the Sun. I cover ALL my ink with the highest SPF I can find. Usually 80. I have mostly black and gray, but I have a colorful dragon on my right shoulder. It’s blue with some yellow, and originally, it had white smoke coming from It’s nostrils that made the smoke surrounding it. I think I was 17–18, when I got it. I’m 42 now… It still looks as if it’s kinda new. Just lost the white over the years.

Well. Actually. I just looked at it. The yellow is mostly gone too…
May I ask, is there a specific image you are thinking about?

To show detailed work, you need to go big. The bigger, the more potential for the best detail. Lines too close together tend to “bleed” into each other.
So. You may need to consider a large area, for maximum quality, OR go with a part of the image on a smaller area of your body…

A good tattoo artist will take the time to think about where the image will line up best, with your body’s natural shapes…

@MrGrimm888 Google “water colored tattoos”.

I have six. I don’t need general ink advice. I need advice specific to this style.

I don’t have any watercolor tattoos myself. Though I’ve heard they’re more prone to fading since they have less ink.

I have a tattoo in white ink from 20+ years ago. And it’s basically just a scar at this point.

Yeah, that’s why I never went for white. :-(

Apologies.
Coincidentally, my dragon is what Google describes them as.

The blue parts are mixed with greens, grays, and whites. Again. It used to be far more impressive, but so was I, esthetically.~
It’s my only ink, that I had done with so many different types of needles. The artist literally called three different types he used “brush points.”(Haven’t heard that term before,or since.)
They were wide, with multiple needles. As I watched, and we talked, I noticed how he overlapped all the different colors. I was actually more than worried for the last three or four hours. It looked sloppy, and it didn’t look like his method was going to have my desired effect. However. After I had it burned in the ink laid down nicely, and the colors did indeed mix well.
The healing process was anomalous though. The whole thing kind of crusted up, and big colorful scabs fell off after a few days. The end result was great. It was just like the examples I saw on Google. As I mentioned though. It lost the yellows and whites that really made it pop. It still looks great, just different.

All my other ones were done with single needles, and gone over at least twice. They were far more painful, but they seem like they are deeper, or something. They all look precisely as they did when they were new.
The single needle method definitely takes way longer too…