Water Heater Tank Issue

I feel the need for some water catchment on my front porch.
I have a water heater tank ready to be stripped and repurposed.
After it is stripped, I plan on cutting a hole just large enough to fit a bucket filter down into.
The issue is the water tanks central chimney:
I can leave it long, poked through a hole in the bottom of the filter bucket, or cut it short, plug it up with water stop cement , or any number of other things, but I was hoping there was something clever to do with it.

Any ideas?

I see your dilemma. The chimney is totally in the way when repurposing these heaters. With the char kiln, I would have cut it out. But for water storage, it's tough to get it out and create a reliable seal.

Would it be possible to daisy chain the output of the blue barrel to the input of the heater? Then you wouldn't need a second filter.

Well, the blue barrel "lives" in the back yard by the chicken composting space, while the tank was going to the front porch.
A new blue barrel would mean doing plumbing I wanted to avoid...

I think I might cool my jets and look for another derelict water heater, one that is electric.
That would allow me to install a  bucket filter, and then daisy chain  as many other tanks as I want onto that one.
I could even use the entire first tank as a filter, and plant willow in it...
I wouldn't need to cut holes any of the other tanks at all.
If the tanks remain unpunctured I could take place them at varying heights without the lowest tank overflowing.

I think I will strip this one down and lay it down in the backyard.
I can fill it from the blue barrel, like you suggested, and  maybe use it to quench my biochar trough.
I've been  worried about the chemicals in the city water being trapped in the char and suppressing the growth of soil life.
I might even be able to recycle the water after the quench.

Thanks for the feed back!
I still have no clever use for the chimney, but I do have better plan than before.