Bengaluru
This list of FAQs answers some of the most common questions that arise when digging a borewell.
What is the diameter of the borewell casing?
The casing is the metal/ plastic section that is generally visible to some extent above the ground. Please refer picture for better understanding
Drinking water standards for each of the parameters
|
TDS (ppm) |
pH |
EC |
Nitrates mg/l |
Nitrites mg/l |
Ammonia mg/l |
Phosphate mg/l |
Iron mg/l |
Calcium hardness mg/l |
| Acceptable limits |
500 |
6.5-8.5 |
N.A |
45 |
3 |
0.5 |
0 |
0.3 |
200 |
| Permissible Limits |
2000 |
No Relaxarion |
N.A. |
No Relaxataion |
No Relaxation |
No Relaxation |
5 |
No Relaxation |
600 |
EC: Electrical Conductivity
What is static water level in the borewell?
Static Water Level (SWL) is generally expressed as the distance from the ground surface to the water level in the well. Static water level (SWL) is the level at which water stands in a well when no water is being removed from the aquifer – pumping from the well itself or from nearby wells.
What is borewell yield?
A common way to describe the yield of a new borewell is in ‘inches’ measured by the free, unrestrained flow of water from a borewell over a 90 degree ‘V’ notch. The basic principle is that the discharge is directly related to the height of the water level from the bottom of the V notch.
h – Height of water level from the bottom of the V
Based on certain equations and formulae, the height ‘h’ in inches is converted to discharge rate in litres per hour.
The following table indicates the conversion of the yield in ‘inches’ to a discharge rate in litres per hour.
| V-Notch Reading in Inches |
Approximate Discharge Rate
in l.p.h. |
Class |
| 1/2 |
95.40 |
Low Yield |
| 3/4 |
261.00 |
| 1 |
597.00 |
| 1 1/4 |
1,045.00 |
Average Yield |
| 1 1/2 |
1,650.00 |
| 1 3/4 |
2,425.00 |
| 2 |
3,382.00 |
High Yield |
| 2 1/4 |
4,558.80 |
| 2 1/2 |
5,919.00 |
| 2 3/4 |
7,501.00 |
| 3 |
9,329.00 |
Very High Yield |
| 3 1/4 |
11,402.60 |
| 3 1/2 |
13,720.00 |
| 3 3/4 |
16,284.60 |
| 4 |
19,148.00 |
Superlative Yield |
| 4 1/4 |
22,285.60 |
| 4 1/2 |
28,695.20 |
| 4 3/4 |
29,459.20 |
| 5 |
33,350.00 |
| 5 1/4 |
37,914.00 |
| 5 1/2 |
42,551.00 |
| 5 3/4 |
47,461.00 |
| 6 |
52,644.00 |
| 6 1/4 |
58,372.00 |
| 6 1/2 |
64,373.00 |
| 6 3/4 |
70,919.00 |
| 7 |
77,464.00 |
| 7 1/4 |
84,557.00 |
| 7 1/2 |
92,195.00 |
| 7 3/4 |
1,00,105.00 |
| 8 |
1,08,288.00 |
At what depths can you detect a change in colour/size of the soil strate observed during the drilling of the borewell?
For instance the top 10 -20 feet would be the top soil and would be dark reddish brown color while at depths beyond 20 ft, the color could change to light brown or greyish. Any pictures taken during the drilling would be awesome!
After the drilling of the borewell was complete, what was the stable water level?
During the borewell drilling, while the rig drills through hard rock substrate, it will come across fissures/ cracks in the rock through which water is discharged at high pressure into the borehole and due to which the water level rises up quite significantly in the borehole. After 3-5 days of drilling, the water level would stabilize and this is the static water level.
What is the level at which water was struck during the drilling of the borewell?
During the borewell drilling process, water could have been struck at multiple depths with varying yields. The borewell driller would have given this information. Please refer picture for better understanding
What is the casing material and what is the depth of the casing?
The casing material could be Galvanized Iron or PVC and the casing would be inserted till a depth where a substrate becomes hard rock. Please refer picture for better understanding
What is the total depth of a borewell?
This refers to the total depth to which drilling was done. Please refer picture for better understanding
What is the diameter of the borewell casing?
The casing is the metal/ plastic section that is generally visible to some extent above the ground. Please refer picture for better understanding
