Yes, in the thought experiment it runs underwater. It's fine though because it can run underwater in both cases, so that doesn't ruin the symmetry. The article

Yes, in the thought experiment it runs underwater. It's fine though because it can run underwater in both cases, so that doesn't ruin the symmetry. The article implies a situation where the pump is running in the opposite direction as normal, sucking the water in. That's not time-reversed though (eg in the time reversed version, the pump generates electricity instead of consuming it, because the water is pushing it instead of it pushing the water)