This list of FAQs answers some of the most common questions that arise when digging a borewell.
1. 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
2. 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
3. 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
4. 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
5. 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.
6. 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!
7. 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
|1 1/4||1,045.00||Average Yield|
|3||9,329.00||Very High Yield|
8. 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.
9. 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|
|Permissible Limits||2000||No Relaxarion||N.A.||No Relaxataion||No Relaxation||No Relaxation||5||No Relaxation||600|
EC: Electrical Conductivity
10. Brief descriptions of each of the water quality indicators
1. Ammonia: When it is present above the acceptable limits, sewage or industrial contamination can be indicated. It is also indicative of fecal contamination.
2. Electrical Conductivity (EC): the conductivity of a water is an expression of its ability to conduct
electric current. EC measures total dissolved solids in the water. To elaborate more, distilled water does not contain dissolved salts and, as a result, it does not conduct electricity and has an electrical conductivity of zero. The higher the dissolved salt/ion concentration, the more conductive the sample and hence the higher the conductivity reading. This parameter is a mere indication of presence of dissolved solids in water.
3. Calcium Hardness is the expression of the results of the measurement of calcium only, as mg/l CaCO3. The chief disadvantages of hard waters are that they neutralize the lathering power of soap (though not modern detergent formulations) and, more important, that they can cause blockage of pipes. Hard water otherwise hasn’t found to have any extreme health impacts.
4. Iron: No harmful health effects due to presence of high Iron. The problems are usually aesthetic like presence of different color, taste of water may change, etc.
5. Nitrate: Presence of nitrate indicates existence of waste discharges and/or artificial fertilizers. Very high concentration of nitrates above acceptable limits is hazardous for infants (Blue Baby Syndrome).
6. Nitrite: Chemically during oxidation of Ammonia to Nitrate, Nitrite is formed. Waters which show any appreciable amounts of nitrite are regarded as being of highly questionable quality. Values greater than acceptable limits may indicate sewage pollution.
7. Phosphates: Phosphorus occurs widely in nature in plants. It is widely used as an agricultural fertiliser and as a major constituent of detergents, particularly those for domestic use. Though there is no significant health hazard due to presence of phosphorus in drinking water, phosphorus is one of the causes of eutrophication of lakes, rivers.
8. Total dissolved solids (TDS): High TDS level indicates that water may be Saline. Although TDS is not generally considered a primary pollutant (e.g. it is not deemed to be associated with health effects) it is used as an indication of aesthetic characteristics of drinking water. Elevated total dissolved solids can result in your water having a bitter or salty taste; result in incrustations, films, or precipitates on fixtures; corrosion of fixtures, and reduced efficiency of water filter and equipment
9. pH: Drinking water should have a pH between 6.5 and 8.5.