Having worked with, seen and spoken to numerous borewell owners, it is apparent that the borewells that yield well; say about more than 60,000 litres of water per day (that are used by layouts, tanker operators, industries etc) are those that are shallower than 800ft. Its not the 1000+ft borewells that yield copious amounts of water. Even if it is a 1000+ft borewell that is yielding a lot of water, a camera inspection will reveal that actually its the shallower cracks that yield more water. Take a look at the attached picture to somewhat make sense of Bangalore’s geology and to see how water comes into a borewell. It does seem more UNLIKELY for water to be available at greater depths
The general perception is that deeper borewells yield more and hence people dig deeper. But the contrary is true. In fact as you dig deeper than 600ft the number of naturally occurring cracks in the rock formations reduce and hence the water availability also reduces. A deep borewell might be able to provide lifeline water to a home of about 500litres per day but very unlikely that it is a 100,000 litres per day borewell. Its the shallower borewells that yield more water.