Well Casing, Grouting, and Gravel Packing
By Bestcare Borehole Drilling
A borehole that’s drilled well but finished poorly won’t last. Well casing, along with grouting and gravel packing, is what turns an open hole into a stable, long-term water source that resists collapse, silting, and contamination from surface water intrusion. This stage gets far less attention from property owners than the drilling itself, but it’s arguably more important to how long the borehole actually lasts. Bestcare Borehole Drilling treats casing and completion work as a technical discipline in its own right, not an afterthought once drilling wraps up.
Casing lines the borehole to prevent wall collapse and seals off unwanted water zones, while grouting fills the space between the casing and the borehole wall to prevent surface contaminants from migrating down into the aquifer. Gravel packing supports the screened sections, filtering out fine sediment while allowing water to flow freely into the borehole. Get any of these wrong, and the consequences show up gradually: sand in the pump, declining yield, or contaminated water years down the line.
Processes Involved in Casing, Grouting, and Gravel Packing
| # | Process | Purpose |
|---|---|---|
| 1 | Casing Material & Diameter Selection | Matches casing type and size to bore diameter and depth |
| 2 | Casing Installation | Lines the borehole to prevent collapse and isolate zones |
| 3 | Screen Placement | Positions perforated sections at confirmed water-bearing zones |
| 4 | Gravel Packing | Fills the annular space around screens to filter sediment |
| 5 | Grouting & Sanitary Seal | Seals the upper annular space to prevent surface contamination |
| 6 | Development & Flushing | Clears drilling residue and fine particles from the completed borehole |
1. Casing Material & Diameter Selection
Casing choice, typically uPVC or steel depending on depth and ground pressure, is matched to the actual bore diameter and the geological conditions logged during drilling. Undersized or mismatched casing is one of the more common shortcuts taken by less careful contractors, and it shortens the working life of the borehole considerably.
2. Casing Installation
Casing is lowered into the borehole in sections, centered carefully to maintain even spacing against the bore wall. Proper centering matters for the grouting and gravel packing stages that follow, since uneven placement leaves weak points where contamination or collapse risk is higher.
3. Screen Placement
Screened sections, perforated to allow water in while filtering out larger particles, are positioned exactly at the water-bearing zones identified during drilling and logging. This is where the strata log taken during drilling becomes directly useful, ensuring screens align with the actual aquifer rather than an estimated position.
4. Gravel Packing
Graded gravel is placed in the annular space around the screened sections, acting as an additional filter layer that keeps fine sand and silt from entering the borehole while still allowing water through freely. Correct gravel sizing relative to the screen slot width is what prevents both sediment ingress and screen clogging over time.
5. Grouting & Sanitary Seal
Above the gravel pack, the remaining annular space near the surface is sealed with cement grout to block surface water and contaminants from migrating down alongside the casing into the aquifer. This sanitary seal is one of the most important, and most frequently under-done, steps in borehole completion.
6. Development & Flushing
After casing and sealing, the borehole is developed by flushing and surging to clear out drilling mud, fine sediment, and any residual particles left in the formation. This step improves water clarity and helps the borehole reach its full potential yield before pump installation begins.
Estimated Cost of Casing, Grouting, and Gravel Packing Services
| Service | Estimated Cost (KES per meter, unless noted) |
|---|---|
| uPVC casing supply & installation | 1,800 – 2,800 |
| Steel casing supply & installation | 3,500 – 5,500 |
| Screen sections (per section) | 3,000 – 5,000 |
| Gravel packing | 1,000 – 1,800 |
| Grouting & sanitary seal (lump sum) | 15,000 – 30,000 |
| Development & flushing (lump sum) | 10,000 – 20,000 |
Costs depend on casing material chosen, total depth, and the number of screened sections required.
Frequently Asked Questions
1. What’s the difference between uPVC and steel casing? uPVC is more affordable and resistant to corrosion, suited to most standard depths, while steel offers greater structural strength for deeper or more unstable formations.
2. Why is grouting necessary if the casing already lines the hole? Casing alone doesn’t seal the space between itself and the borehole wall. Without grouting, surface water and contaminants can travel down alongside the casing into the aquifer.
3. How is screen placement determined? Screen position is based on the strata log recorded during drilling, aligning perforated sections with confirmed water-bearing zones rather than an estimate.
4. What happens if gravel packing is skipped? Without it, fine sand and sediment are more likely to enter the borehole, leading to pump wear, reduced yield, and cloudy water over time.
5. How long does the casing and completion process take? Typically one to two days after drilling is complete, depending on total depth and the number of screened sections involved.
5 Reasons to Choose Bestcare Borehole Drilling
- Depth and geology-matched casing — material and diameter are selected based on actual conditions, not a default spec.
- Precise screen placement — informed directly by strata logs taken during drilling, not guesswork.
- Proper sanitary sealing — grouting is treated as essential, not optional, protecting long-term water quality.
- Thorough development process — boreholes are flushed and developed to reach genuine potential yield before handover.
- Long-term durability focus — casing and completion work is done to standards that support decades of use, not just initial commissioning.
The drilling gets the headlines, but casing, grouting, and gravel packing are what determine whether a borehole is still delivering clean, reliable water ten or fifteen years later. Bestcare Borehole Drilling treats this stage with the technical care it actually requires.
