[Watertight recipient (I see Holes in slice)]

Hello,
I need to make a watertight recipient, and I have tried several times and it leaks.
Zooming in the slices I see that there is some holes, as can be seen in the picture.

 

Does anyone know how can I get rid of that and build solid walls?

 

Any help will be much apretiated!

Thanks in advance.
F.

vase.stl