You obviously have moisture getting into an exterior block wall.
It may be even worse because it sounds as if this wall is not
facing a conditioned space. Water alone will not harm the block.
If you live where it freezes, the ice will break the block. The
green algae will probably not harm the block.

The best thing would be to dig up the outside and waterproof. If
your area drain is working, I think I would poke a hole in the
bottom cells to let standing water out and a discreet hole above
grade to encourage air movement. I would guess that the block is
painted and sealed up for it to be holding water.

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______________________________
Keep the whole world singing . . . .
DanG (remove the sevens)




"Bill Stock" wrote in message
...
I had too drill a couple of 4" holes through a concrete block
wall and I lost the center bit for the coring saw twice. The
first time I managed to fish it out with a magnet. That's when I
noticed that the bottom row of blocks has about 6" of water in
them. I thought this was a little strange, should I worry about
it? One wall has a funky green colouring near the bottom, looks
like algae, but it's probably mold.

I was going to drill some half inch holes to drain the water,
but I'm not sure this is a bright idea? The room is an entryway
for an outside stairwell and has it's own drain.