I have a large ornamental two-tear water fountain in my backyard. There are no drains in either large bowl making a clean up very difficult. If I could saw (drill) a large 1 1/2" - 2" hole in the bowl, I could more easily flush out the dirty water. Finding a plug to reseal it should not be a problem.

The bowls are made of concrete, but it is a very fine grain aggregate and may even be laced with a fiber glass fabric.

Does anyone have any suggestion for cutting such a large hole in the concrete? Thickness at the point where I need the drain is about 2".

 

Depending on how close you plan to go to the edge of the fountain, I would consider drilling a series of holes close together in a circle using a small diamater drill bit, then work your bit over to connect the holes you've just drilled. Mark it out first with a marker and follow along your mark.

You could clean up your work with a Dremel tool or a fine file.

Obviously a main concern is breaking your fountain, and I think you'd be better served using a smaller bit than trying to get it all at once with a large one.

Do you think you'll be able to drill a spot that is rather flat? Curved areas are more likely to give you a problem.

 

The obvious always evades me. The multi-drill hole approach may work well. Thanks.