Let’s take just ten feet between your static water level and the bottom of your well as an example. That would be an unusually small amount of water. It leaves a very small buffer of water to pump that would be quickly exhausted if you had a modest recovery rate. (The recovery rate is the speed at which the well refills after pumping.) And it leaves very little safety margin to allow for seasonal variations in water level.

Because there is so little margin of error for this well, it would be prudent to make very sure about the exact water level and depth.

You should also ask the person who drilled your well what the recovery rate is. With a recovery rate significantly higher than 3 GPM (which is the capacity of our smaller 100L pump), installing that model in your well would be workable, even with that very small buffer.

If that is not viable, another option is to drill the well deeper, at least a few tens of feet. You can consult with your well company on this. It may be a good idea anyway, as water levels have dropped in many parts of the country.

Speaking with the driller, or someone else who understands your well, is critical to answering another question: Does the water level fluctuate significantly throughout the year? If the static water level is (as you say) 90 feet, but at the driest part of the year is 100, then you do not have a viable well at all, unless you drill further down.