How much depth is required to fix submersible pump?

The water yeild in our borewell was around 1.25 inch at 570 sft. We further bored it upto 740 sft but there was no sign of second yeild. However, our neighbors got first yeild at 990 sft. We did not want to go further deep and hence we stopped at 740sft. The borewell is for domestic purpose. Now can I go for single phase motor, at a depth of 650sf? Also, one or two feet before the fracture point at 570sft, we got some boulders. Is this due to water yeild point or will have slit issue in later stages. Please clarify. Thank you.

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