Depth ranges by geology
| Zone | Typical depth | Where you'll find it |
|---|---|---|
| Alluvial / coastal | 30 – 80 m (100 – 260 ft) | Indo-Gangetic plain, coastal Tamil Nadu, Kerala, Bengal |
| Soft / weathered rock | 60 – 150 m (200 – 500 ft) | Central India, parts of Maharashtra, Madhya Pradesh |
| Hard rock (granite/basalt) | 120 – 250+ m (400 – 800+ ft) | Most of Karnataka, Tamil Nadu, Andhra interior, Telangana |
The recharge factor adjusts these ranges. "Good recharge" pushes the low end of the range; "poor recharge" pushes towards (and past) the high end — over-exploited aquifers may require depths well beyond the typical range.
Things this calculator does NOT account for
- Local water-table depth — varies by sub-region; can range from 5 m to 200 m below surface even within the same district.
- Specific aquifer location — productive aquifers often lie at specific fracture or lithology depths that only a survey can identify.
- Seasonal variation — post-monsoon levels vs pre-monsoon can differ by 5–30 m.
- Government regulation — in over-exploited blocks, drilling permits and Central Ground Water Authority approvals may be required regardless of need.
FAQ
How long does a borewell last?
A properly cased and maintained borewell can yield water for 15–30 years. Yield typically declines over time as the aquifer level falls or surrounding extraction increases.
What is casing pipe and why is it important?
Casing is the steel or PVC pipe that lines the upper section of the borewell to prevent collapse of loose strata and contamination from surface runoff. Typical casing depth: 30–50 ft (alluvial/soft) or to the top of competent rock (hard rock zones).
What's a typical drilling cost?
Indicative: ₹70–150 per running foot (varies by location and rock type), plus ₹10,000–30,000 for casing pipe and ₹15,000–60,000+ for the submersible pump and panel. Hard-rock drilling is significantly more expensive than alluvial.