In Donholm, Nairobi County, Kisima Well Drillers engineered an investor-grade water-selling borehole that goes deliberately beyond standard. We drilled the open hole at 10 inches, cased it with 8-inch steel, took it down to 250 metres, and equipped it for a sustained yield of 18 m³ per hour. Today the site loads at least 10 water tanker trucks every day — a working blueprint for anyone who wants to invest in selling water in Nairobi.
Donholm sits at the busy edge of Embakasi, Nairobi County — a high-density estate ring of apartments, schools, churches, eateries and factories that all need water faster than the piped network can supply. The opportunity, for an investor, is obvious: drill once, sell every day. The trap is just as obvious: drill cheap, drill standard, and watch the business die when the aquifer drops or the pump can't keep up.
Our client did not want a domestic borehole pretending to be commercial. They wanted infrastructure — a single asset capable of feeding tanker trucks on a queue, day after day, for the next 20–30 years. That meant rejecting the default 8-inch drill + 6-inch casing configuration you see across most Nairobi compounds, and going one full stage bigger: 10-inch open hole, 8-inch steel casing, 250 m depth.
The result is the borehole on this page. Below we break down — to the inch — why it was built the way it was built, what it produces, what it earns, and what an investor should copy if they want to do the same in any other busy part of Nairobi.
Standard Nairobi boreholes drill an 8-inch hole and slip in a 6-inch casing. That works for a homestead. For a borehole that has to load tanker trucks all day, every day, those numbers leave no headroom — no room for a bigger pump, no room for a thicker gravel pack, no room for years of natural water-level decline. We chose 10 inches drilled and 8 inches cased on purpose.
An 8-inch casing comfortably houses a 6-inch submersible motor and pump assembly rated at 15–25 m³/hr. A 6-inch casing forces you down to a 4-inch pump (≤8 m³/hr) — not enough to load 10 trucks a day without overheating.
With the hole drilled at 10″ and the casing at 8″, we have ≈25 mm clearance on every side. That gap is filled with graded gravel pack so water enters the casing slowly, fines stay out, and the well screen never silts up.
Bigger open area at the screens drops the water entry velocity below the silt-mobilising threshold. Translation: sand-free water, less pump wear, and a borehole that still produces in 20 years instead of dying in 5.
As more boreholes are drilled around Donholm, static water levels drop year-on-year. A larger casing lets us set the pump deeper later — without having to redrill the whole borehole.
The wider annulus is grouted with cement at the upper portion to seal off surface contaminants — critical when you're selling water and answering to public-health authorities.
| Spec | Standard domestic borehole | Donholm commercial build |
|---|---|---|
| Open-hole drill diameter | 8 inches (203 mm) | 10 inches (254 mm) — +25% bigger |
| Casing diameter | 6 inches (152 mm) | 8 inches (203 mm) — +33% bigger |
| Typical pump fit | 4″ submersible · 4–8 m³/hr | 6″ submersible · 15–25 m³/hr |
| Gravel-pack annulus | ≈ 12–13 mm per side | ≈ 25 mm per side |
| Drawdown tolerance | Limited — re-deepening needed in 5–8 yrs | Years of pump-setting headroom |
| Best use case | Single home, small compound | Commercial water vending, tanker loading, estates |
Nairobi County now hosts thousands of registered (and many unregistered) boreholes pulling from the same regional aquifer system — the Athi Series sediments, the Nairobi Trachyte and the underlying Athi tuffs and lake beds. Densely-drilled areas like Donholm, Umoja, Embakasi and Tena are putting real pressure on shallow aquifers. The smart move is not to compete shallow — it is to go deeper, wider and cleaner.
Across eastern Nairobi, static water levels have been dropping roughly 1–2 metres per year in heavily-drilled neighbourhoods. A borehole designed for today's water level dries up under tomorrow's demand. Ours was set deep with a wide casing so the pump can be lowered as needed for the next 20+ years.
Most cheap Nairobi boreholes stop at 100–150 m and tap the upper Athi sediments. We pushed past those layers into deeper trachyte fractures and the Athi Series aquifers, which still hold strong, recharging volume — exactly what a commercial operation needs.
You cannot pull 18 m³/hr through a narrow casing. The 10″/8″ build was chosen specifically so the casing isn't a bottleneck — the aquifer feeds the screens, the screens feed the casing, and a 6-inch submersible lifts it without choking the column.
Every commercial borehole in Nairobi County must pass through the Water Resources Authority (WRA) drilling and discharge permits and NEMA environmental screening. We sized this borehole knowing the volumes we'd declare on the WRA discharge permit — so the legal yield matches the engineered yield.
Drilling in Donholm means cutting through a layered story: red lateritic soils on top, then weathered tuff and clay, then the dense Nairobi Trachyte, then the productive Athi Series. Our hydrogeologist's prediction matched the rig log almost rod-for-rod. Here is what the borehole actually looked like as it went down.
Sticky, sometimes collapsing — drilled with mud rotary and supported by the upper section of 8-inch surface steel casing grouted in cement to seal out any pit-latrine or stormwater contamination from the surface.
Switched to DTH (down-the-hole) hammer. Faster penetration, walls stayed clean. Some minor water shows but nothing worth setting screens against — we pushed on.
Hard, blocky rock. A weaker borehole stops here. The 10-inch hammer earned its keep — clean cutting, straight verticality, no collapse.
Confirmed water at ~185 m. Recorded but not relied on; we pushed deeper to find the stronger, more recoverable horizon below.
Strong, sustained inflow across a fractured zone. This is where the commercial yield actually lives — and where we placed the screened section of the 8-inch casing and the pump intake above it.
After completion, the borehole was developed and test-pumped to confirm what an investor needs to hear: a sustained safe yield, not just a flashy first-strike number. Drawdown stabilised, recovery was strong, and the borehole was certified for commercial use at 18 m³/hr.
That's 432 m³ per 24 hours of theoretical maximum — far more than we ever need. We deliberately operate at ~6 hours/day to keep the aquifer healthy and the asset long-lived.
A water-selling borehole only earns when trucks can pull in, fill and pull out fast. We built a dedicated loading bay with a 100 mm (4-inch) galvanised steel filling line, a quick-action valve, a chlorination dosing point, and a hard-standing apron sized for a 10,000-litre tanker to manoeuvre cleanly.
The borehole pumps directly into an elevated buffer tank so trucks fill by gravity flow — not by waiting on the pump. That means each truck fills in roughly 10–14 minutes, the pump cycles efficiently rather than running constantly, and the aquifer is never stressed for a queue.
Investors keep asking the same question — "is selling water actually profitable in Nairobi?" Yes. Done correctly, a commercial borehole pays itself back inside 12 months and continues to earn for two decades. Here is the working model from Donholm, figures expressed conservatively in Kenyan shillings.
10 tanker trucks × 10,000 litres each. Achieved comfortably within ~6 hrs of pumping.
Typical Nairobi 10,000-litre tanker sale price depending on distance — we model KES 6,000.
10 trucks at KES 6,000. Domestic and estate sales come on top of this.
30 operating days. Real sites typically achieve 26–30 productive days/month.
KPLC power, attendant wages, light maintenance, chlorination, periodic pump service.
After realistic operating costs, conservative ramp-up and seasonal fluctuation.
Survey, WRA/NEMA permits, drilling 10″/250 m, 8″ casing, pump, panels, tanks, loading bay.
At full ramp. Even at 50% utilisation, payback is well inside a single year.
VES geophysics + desk study to identify the deep aquifer target and the safest drill point on the plot.
Drilling authorisation, abstraction permit and environmental screening before a single rod goes down.
Mud rotary through overburden, DTH hammer through trachyte, screens placed across the deep production zone.
Steel casing installed, gravel pack placed in the annulus, cement seal at surface, then airlift & surge development until water runs clear.
6″ submersible pump, control panel with dry-run protection, elevated buffer tank, truck filling line and chlorination point.
Selling water without proper permits, a verified water-quality test and a clean abstraction record is the fastest way to get a business shut down. We delivered the Donholm borehole compliance-first — so the asset can earn legally for its entire economic life.
Water Resources Authority authorisation issued before drilling — site-specific, geo-referenced and lodged.
Abstraction permit sized to the engineered yield, so the legal volume matches the operational one.
Environmental project report screened by NEMA — required for commercial water vending in Nairobi County.
Accredited lab test on potable parameters: pH, TDS, fluoride, hardness, microbiology. Test report on file.
Photos from the Donholm, Nairobi County borehole during drilling, casing and loading-bay operation.
We were told to drill an 8-inch hole with 6-inch casing like everyone else in the estate. Kisima insisted we go 10 by 8 and push to 250 metres. Eighteen months later, ten trucks are loading from us every day — and the borehole has paid itself back twice.
Because a commercial water-selling borehole needs to host a much bigger pump than a domestic one, tolerate decades of pumping, and survive the falling water table that comes with dense Nairobi drilling. A 10-inch open hole gives a true 8-inch finished casing room to sit with a proper gravel pack on every side. The 8-inch casing then accepts a 6-inch high-flow submersible capable of 15–25 m³/hr — which is exactly what you need to load 10+ tanker trucks a day comfortably.
Shallow Nairobi aquifers are already over-pumped. Two cheap 100 m boreholes might give 4 m³/hr each at first, then dry up together when a neighbour drills nearby. One deep, well-engineered borehole into the Athi Series gives sustained, predictable, regulated yield — and is a single asset to maintain instead of two depreciating ones.
A standard tanker carries 10,000 litres (10 m³). At 18 m³/hr the borehole can fill that tanker from direct pumping in ~33 minutes, or from a buffer tank in 10–14 minutes. The site comfortably handles 10 tankers a day with capacity to spare.
For an oversized commercial build like Donholm — full hydrogeological survey, WRA/NEMA permits, 10-inch × 250 m drilling, 8-inch steel casing, gravel pack, 6-inch submersible pump, control panel, elevated buffer tank, truck loading line and a small attendant kiosk — you should plan a budget in the KES 3–4 million range. We give every client a line-itemed quote before commitment.
Yes — but only if it's tested. Every Kisima commercial borehole is followed by an accredited water-quality test on potable parameters. Where required we install in-line dosing (chlorination, sometimes pH adjustment or fluoride media). The Donholm water passes Kenyan drinking-water standards and is sold legally to tanker operators serving Donholm, Embakasi, Tena, Umoja and surrounding estates.
Typical timeline: 2 weeks for survey and permits, 5–8 days of active drilling and casing, 2–3 days of test pumping and water-quality work, then 1–2 weeks for equipping and the loading bay. From signed contract to first truck loaded is usually 5–7 weeks.
Yes. Once you're seriously evaluating, we arrange a site visit (where the client allows) so you can see the build, the loading bay and the trucks dispatching in real time. Investors find it answers more questions in 20 minutes than any brochure can.
If you're an investor, estate owner or community group eyeing the water-selling market in Nairobi or any major Kenyan town — we'll survey, drill, equip and commission your commercial borehole with the same engineering discipline you've just read about.
The Donholm commercial water borehole sits in Donholm estate, Embakasi sub-county, Nairobi County, Kenya — a strategic catchment for tanker operators serving Donholm, Tena, Umoja, Buruburu, Embakasi and the wider Eastlands corridor.
Donholm commercial water borehole Donholm, Embakasi · Nairobi County
