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[A_Curious_Cat]

Hi.  I seem to be having a problem filling my reservoir.

Partway through filling, the water stopped flowing.  The enter aqueduct before the inverse sump is filled with 7/7 water, but the upper level of the sump and the rest of the aqueduct leading from the sump to the reservoir are dry.  The inverse sump is 7 z-levels below the aqueducts inlet and said inlet is under 7/7 water. 

Help, would be much appreciated.

[mightymushroom]

This is a case where visual aids might be helpful to diagnose your situation.

My first thought is that since the reservoir is lower than the aqueduct inlet, you have installed a pressure reducer along the line to keep the reservoir from overflowing. It may be that it's at too low a z-level. Note that a gravity-fed system stops filling "upward" one z below the effective source level (where the reducer is). It's an easy quirk to get caught by, since behavior is different with pumps (and different from what you'd expect with real-world water).

Side view:

▓       ▓▓▓   ▓
▓        ▓    ▓
▓   ▓▓▓|▓▓    ▓
▓    ▓   ▓    ▓
▓▓▓▓▓▓   ▓▓▓▓▓▓

▓ = Unfilled space
▓ = Original water source at top center
| = location of pressure reducer (diagonal-only passage on same z-level)
▓ = Water after reducer

[A_Curious_Cat]

This is a case where visual aids might be helpful to diagnose your situation.

My first thought is that since the reservoir is lower than the aqueduct inlet, you have installed a pressure reducer along the line to keep the reservoir from overflowing. It may be that it's at too low a z-level. Note that a gravity-fed system stops filling "upward" one z below the effective source level (where the reducer is). It's an easy quirk to get caught by, since behavior is different with pumps (and different from what you'd expect with real-world water).

Side view:

▓       ▓▓▓   ▓
▓        ▓    ▓
▓   ▓▓▓|▓▓    ▓
▓    ▓   ▓    ▓
▓▓▓▓▓▓   ▓▓▓▓▓▓

▓ = Unfilled space
▓ = Original water source at top center
| = location of pressure reducer (diagonal-only passage on same z-level)
▓ = Water after reducer

The reducer (which I can turn on and off in two stages) isn’t until after the inverse sump (right before the outlet bridge into the reservoir).

[mightymushroom]

Okay, so much for the first try. Hmm...

Any other bridges, doors, hatches or floodgates along the path that may have gotten closed accidentally?

Any other chambers, map edges, or exposed aquifer that the water might be draining into?

[A_Curious_Cat]

Okay, so much for the first try. Hmm...

Any other bridges, doors, hatches or floodgates along the path that may have gotten closed accidentally?

Any other chambers, map edges, or exposed aquifer that the water might be draining into?

No and no.  Not that I can see.

[anewaname]

mightymushroom pointed out the things that would do it (obstructions to water flow, an aquifer sponge, or someplace else for the flood to flow).

Check again? or add screenshots? What is your water source?

[PatrikLundell]

Another quirk is that water may fail to flow through vertical bends (definitely n bends, but possibly u bends as well) because DF doesn't realize that water should flow through. Presumably water flow happens only if there's some water that actually moves (i.e. a tile with less than 7/7 water somewhere along the line). I've had perfectly valid setups just fail to get the water through the bend when I've opened the drawbridge downstream of the bend, but so far I've been able to recover by toggling a drawbridge upstream of the bend, as that atom smashes a tile of water, which restarts the flow.

[A_Curious_Cat]

mightymushroom pointed out the things that would do it (obstructions to water flow, an aquifer sponge, or someplace else for the flood to flow).

Check again? or add screenshots? What is your water source?

I’m waiting for technical support from the image hosting site to email me back.  Otherwise, I would have posted something already.

I’m drawing water from a stream in a tropical rainforest.

Another quirk is that water may fail to flow through vertical bends (definitely n bends, but possibly u bends as well) because DF doesn't realize that water should flow through. Presumably water flow happens only if there's some water that actually moves (i.e. a tile with less than 7/7 water somewhere along the line). I've had perfectly valid setups just fail to get the water through the bend when I've opened the drawbridge downstream of the bend, but so far I've been able to recover by toggling a drawbridge upstream of the bend, as that atom smashes a tile of water, which restarts the flow.

I tried what you said, and the flow started and then stopped almost as soon as it started.  The water level in the inverse sump didn’t rise a single bit.

I’m afraid that I may have to abandon this fort.  It’s been my most successful one thus far.  In my next fort, I may install a means to drain the part of the aqueduct that’s upstream of the inverse sump with going through said sump.

But hey… the hospital can clean patients with muddy water, right?…

[mightymushroom]

Water source might be the key thing here. If it's a stream that flows off the map edge, it's probably taking the stream outlet rather than your aqueduct. That is, the pipes fill as long as water drops gravitationally into the hole. However at some point the physics engine stops pathing for falling water. (No doubt there is some form of short circuit built in to save checking every path for every piece of water when most of it will not actually have open space to fall into.) The only pressure trigger remaining is from the stream inflow and it will tend to prefer lateral movement along the watercourse over any "upwards," even when there is open space several z-levels down.

If this is the case your aqueduct is engineered perfectly, it's nature that is incorrect! A common complaint of dwarves.

For one possible solution, you could try some scheme to dam the stream at the downstream map edge, so that the water builds up to 7/7 there and the upstream flow checks more spaces. Only a partial dam is necessary, such that the map edge outflow is less then potential inflow. Caution: this can and will cause water to rise all the way to the starting level, unlike my previous pure gravity diagram.

Or you can try to restart the vertical falling as PatrikLundell suggests. I guess that's not working for you, at least not whatever plan you tried.