Depends on what turbo you have
If you have the old style the ones that have bushes
Not bearings then do away with the water all together

Some roller bearing turbo say they require it

The water jacket was only intended to extend the life
Of a turbo that the owner did not respect
I.e. Nail it cold
Turn straight off hot

Water under pressure boils at 120 degs
Your turbo after a good drive will be generating
Higher temps than that

I used to work at pace for years
Years ago when all this was the next best thing from
Slide bread
Done a load of testing with my car and found that
A turbo cooler was not needed if your rad was up to
The job

And the test showed that a charge cooler did f all if you ran a 500 cooler

That said a charge cooler ain't bad on a rst as it's 3x the size

And if you want to help the oil temp just run
A sebtrap oil cooler not hope that the water will do all the work

As the hotter one will always heat up the colder one

If you really want the turbo water jacket to work you would put
A completely separate water system on it
Or even a Oil filled cooling system