Borewell drilling is commonly measured by depth in feet, and contractors often quote a rate in rupees per foot (₹/ft). Multiply the measured depth by the agreed rate to estimate the basic drilling charge. The final project cost may also include casing, transport, flushing, a pump and other work.
If you are building a house, understanding this calculation will help you read a contractor’s quotation, compare different quotations and ask useful questions before committing your money.
1. What does a borewell contractor measure?
There are three measurements worth understanding before you ask for a quotation.
| Measurement | Common unit | What it tells you |
|---|---|---|
| Borewell depth | Feet (ft) | How deep the hole is drilled |
| Borewell diameter | Inches (in) | How wide the hole is |
| Drilling rate | Rupees per foot (₹/ft) | The agreed charge for each foot drilled |
Depth and diameter are not the same thing. A borewell can be 500 feet deep and have a diameter of 6 inches. The first measurement describes how far down the hole extends; the second describes its width.
Both can affect the work involved and the price. When comparing quotations, check that the drilling rates refer to the same diameter, drilling method and scope of work.
2. How do you calculate the drilling cost?
The simplest calculation is:
Drilling cost = Total depth × Rate per foot
Suppose a contractor quotes ₹120 per foot and the borewell reaches a depth of 500 feet.
| Item | Calculation | Amount |
|---|---|---|
| Drilling depth | 500 feet | — |
| Rate per foot | Agreed quotation | ₹120 |
| Basic drilling charge | 500 × ₹120 | ₹60,000 |
The basic drilling charge in this example is ₹60,000.
This is an illustration of the calculation, not a current market-rate estimate or a quotation for Coimbatore. Actual rates depend on the contractor, equipment, location, diameter, ground conditions and the terms agreed.
There is another important point: 500 feet is an example, not a recommended depth for your property. The depth required at a particular site cannot be established by this arithmetic. It requires appropriate local evidence and professional assessment, and even then the result is not guaranteed.
3. What if the contractor charges different rates at different depths?
Not every quotation uses one flat rate for the entire borewell. Some contractors quote different rates for different depth ranges.
For example, imagine this hypothetical quotation:
| Depth range | Illustrative rate | Calculation |
|---|---|---|
| First 200 feet | ₹100/ft | 200 × ₹100 = ₹20,000 |
| Next 200 feet | ₹120/ft | 200 × ₹120 = ₹24,000 |
| Next 100 feet | ₹140/ft | 100 × ₹140 = ₹14,000 |
| Total: 500 feet | ₹58,000 |
In this example, the total drilling charge is ₹58,000.
Notice that multiplying all 500 feet by the final rate of ₹140 would give ₹70,000. That would be incorrect for this quotation because the higher rate applies only to the final depth range.
When a contractor quotes different rates at different depths, ask exactly where each rate begins and ends. Also ask whether the rate changes according to the depth reached, the material encountered or some other condition.
The numbers above are purely illustrative. Use the actual written quotation for your calculation.
4. Is the drilling charge the total cost of a borewell?
Not necessarily. Drilling is only one part of the project.
Depending on the site and the contractor’s quotation, you may also need to budget for:
- Casing pipes: Pipes installed in sections of the borewell where required by ground conditions and the well design.
- Rig transport and mobilisation: Bringing the drilling equipment to your property.
- Flushing and cleaning: Work performed to remove drilling cuttings and prepare the borewell for assessment or use.
- Pump and installation: The pump, suitable pipes, electrical equipment and installation work.
- Other site expenses: Civil work, electrical connections and other requirements specific to your property.
Do not assume every item is an additional charge. Some contractors include certain services in their drilling rate, while others quote them separately.
The right question is not simply, “What is your rate per foot?”
It is: “What exactly is included in your rate, and what will I have to pay for separately?”
That question makes it easier to compare quotations on equal terms.
5. How can you compare two borewell quotations?
Imagine that one contractor quotes ₹110 per foot and another quotes ₹125 per foot. The first quotation appears cheaper, but that does not necessarily make it the better offer.
Before comparing the totals, check whether both contractors have quoted for:
- The same borewell diameter and drilling method.
- The same depth-based rate structure.
- The same casing specifications and included work.
- The same transport, flushing and other charges.
- The same treatment of taxes, additional work and unexpected ground conditions.
Ask for the terms in writing. A quotation that clearly states what is included is more useful than a low headline rate with uncertain extras.
Also ask how the actual drilled depth will be recorded and how the final bill will be calculated. Keep the written quotation and the final depth record so you can check the arithmetic.
6. Does knowing the drilling rate tell you how deep to drill?
No. These are two separate questions.
The drilling rate tells you how the contractor calculates a charge. It does not tell you how deep your borewell should be.
For a house, the decision about where and how to drill should consider the property’s location, available geological and groundwater information, nearby wells and their seasonal performance, intended water demand, and the advice of qualified local professionals.
A nearby borewell can provide useful information, but its depth alone cannot guarantee the same result on your property. Groundwater conditions can vary over relatively short distances.
Do not choose a drilling depth simply because a neighbour drilled to that depth or because a contractor promises that water will be found there.
7. Feet or metres: which unit should you use?
Borewell drilling quotations in India commonly use feet. Scientific reports and government groundwater publications may use metres.
The conversion is straightforward:
1 foot = 0.3048 metres
For example, a depth of 500 feet is 152.4 metres.
When comparing a contractor’s quotation with a technical report, check the unit before interpreting the numbers. A measurement of 150 metres is not the same as 150 feet.
Before you book a borewell
Ask the contractor for a written quotation that identifies the drilling diameter, rate per foot, any depth-based rate changes, included services, additional charges and the method for recording the final depth.
Then estimate the basic drilling charge using the quoted rate structure. Prepare a separate budget for equipment and other work that is not included.
Most importantly, keep the price calculation separate from the decision about where to drill and how deep to go. One is a matter of arithmetic; the other requires evidence about the site.
Sources and further reading
- Central Ground Water Board (CGWB) — Official groundwater publications and technical reports for understanding groundwater conditions.
- Tamil Nadu Agricultural University (TNAU) — Agricultural and regional information that may help with water planning.
The example rates in this article are hypothetical and are not sourced market prices. No current Coimbatore drilling rate or recommended borewell depth is asserted here.