> We know when water/Air or some thing Travel's trough a tubing or stays there ; exerts a pressure at inside walls of that body ; So, in this situation it is a force from
[ Inside -> outside ].
Yes, but we're talking a gravity feed filter here. At most, it's likely to be a 2m hydrostatic head. It's not thousands of psi...
> Hence Tubes due to their thin walls would crack at joining or where it suits to
The heat shrink tubing in question is commonly used to make a protective outer for cables that are required to flex. I'd say it's low risk.
Even if a hole develops, you could cut the tube down to remove the leak, or patch it with duct tape; it won't be the end of the world. You might have to go back to boiling water, or, shock horror, drink water without treating. <faints>
> So that if however Pump pushes water with more flow
Pump? Again, we're talking about gravity-fed water filters. There's no pump involved.
The other advantage of heat-shrink tubing is that you could shrink it on to the filter...
I'd go with the non-adhesive version.