Author Archives: Raeli Hydro

Underground water tanks are a critical part of water storage infrastructure for homes, estates, commercial buildings, and institutions. Over time, sediment, biofilm, rust, and microbial growth can accumulate on the tank walls and at the bottom, compromising water quality and system performance. Regular water tank cleaning is essential to maintain hygiene, extend the tank’s lifespan, and prevent costly repairs or pipe clogging. Here’s how underground water tank cleaning is professionally carried out, with Raeli Hydro’s step‑by‑step approach.

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Why water tank cleaning matters

An underground water tank rarely sees direct sunlight and is usually hard to inspect visually, so contamination can build up unnoticed for months or even years. Silt, decomposed organic matter, and mineral deposits reduce the effective storage volume and create conditions where bacteria and algae thrive. This directly affects water taste, smell, and safety, especially in multi‑tenant or high‑use buildings. Scheduled water tank cleaning helps avoid these issues before they become visible or cause health complaints from occupants. Raeli Hydro treats water tank cleaning as a core preventive‑maintenance service, not just a reactive fix after water quality deteriorates.

Step 1: Safety and site preparation

Before any tank entry, Raeli Hydro starts with a full safety and risk assessment. Access to underground tanks often involves confined‑space risks, so the team follows standard operating procedures for ventilation, gas testing, and personal protective equipment (PPE). The surrounding area is cordoned off, and power isolation procedures are applied where necessary to prevent accidental pump activation. Once the safety checks are complete, technicians open the manhole cover and set up extraction tools, hoses, and vacuum equipment around the hatch. This preparation phase ensures that water tank cleaning is conducted safely while minimizing disruption to the building or water supply.

Step 2: Emptying the tank and removing loose sludge

The next step in underground water tank cleaning is to drain the stored water and remove as much of the loose sludge as possible. Raeli Hydro uses submersible or peristaltic pumps to discharge water in a controlled way, often directing it through a filtration or settling system so that heavily silt‑laden discharge does not clog the site’s drainage. After the bulk water is removed, specialised vacuum trucks or high‑pressure suction units are used to extract the sludge and floating debris from the tank floor. This step recovers a large portion of the contaminants without the need for immediate manual scrubbing and prepares the surface for a more thorough clean.

Step 3: Manual scrubbing and wall inspection

Once the loose sludge is removed, technicians descend carefully into the tank to perform manual scrubbing of the walls, floor, and internal fittings. Using non‑abrasive brushes and scrapers, they remove algae, biofilm, rust patches, and stubborn deposits that pumps cannot dislodge. During this water tank cleaning phase, Raeli Hydro also inspects the tank structure for cracks, leaks, corrosion, or worn joints that could lead to future contamination. Silicone‑based sealants or epoxy repairs can be applied at this stage if minor defects are found, ensuring the tank remains watertight once refilled.

Step 4: High‑pressure cleaning and disinfection

After mechanical scrubbing, Raeli Hydro employs high‑pressure cleaning techniques to rinse away loosened debris and ensure the tank surface is smooth and hygienic. Clean water (often drawn from an external source) is directed through high‑pressure jets that can reach every corner, including the ceiling and around inlet/outlet pipes. This step is crucial because residual biofilm can quickly regrow if not fully removed. Once the tank is visibly clean, a disinfection phase follows, typically using food‑grade chlorine or approved biocidal solutions formulated for potable‑water systems. The disinfectant is circulated throughout the tank and allowed to dwell for a specified contact time to eliminate bacteria, viruses, and other pathogens. This disinfection procedure is an integral part of professional water tank cleaning and ensures the water is safe for human use once the tank is refilled.

Step 5: Flushing, refilling, and testing

After the contact period, the disinfectant water is safely discharged, followed by one or more rinse cycles using clean water until the residual chlorine or chemical levels fall within safe limits. Only then does Raeli Hydro begin refilling the tank, taking care to use good‑quality source water and avoiding any back‑contamination from the supply line. Once the tank reaches its normal operating level, a small sample is collected for testing if required by the client. Tests can include residual chlorine, pH, turbidity, and microbiological checks, depending on the building’s use (residential, hospital, school, hotel, etc.). This quality‑control layer ensures that the water tank cleaning service delivers measurable improvements in water safety, not just visual cleanliness.

Step 6: Documentation and maintenance planning

Raeli Hydro treats every water tank cleaning job as part of a broader water‑quality management plan. After the tank is cleaned and refilled, a brief service report is prepared. This report typically includes the tank size, location, sludge volume removed, visible defects observed, any repairs performed, and the disinfectant used, along with recommendations for the next cleaning interval. For underground tanks that supply larger estates or institutions, Raeli Hydro often suggests a periodic water tank cleaning schedule—commonly every 6–12 months, depending on usage, inlet water quality, and local environmental conditions. This proactive approach reduces the risk of sudden water‑quality issues and keeps the system running efficiently.

How often should underground tanks be cleaned?

The ideal frequency for water tank cleaning depends on several factors, including tank size, whether the tank receives rainwater or borehole‑water, and how stable the source water quality is. In areas with high sediment load or where water is exposed to organic debris (for example, harvested rainwater), more frequent cleaning—quarterly or twice‑yearly—may be warranted. Conversely, well‑maintained underground tanks receiving pre‑treated borehole or municipal water may only need water tank cleaning every 12–18 months, provided there are no visible signs of contamination or reduced flow. Raeli Hydro evaluates each site individually and tailors the water tank cleaning interval to the client’s risk profile and usage pattern.

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Cleaning Companies in Nairobi

Why Raeli Hydro’s approach stands out

Raeli Hydro combines technical expertise, local experience, and safety‑conscious procedures to deliver consistent water tank cleaning results. The team uses calibrated equipment, safe‑use chemicals, and documented processes that align with public‑health and water‑safety standards. By integrating inspection, repair, and preventive‑maintenance advice into every underground water tank cleaning job, Raeli Hydro helps clients avoid not only dirty water but also costly leaks, pump failures, and emergency repairs. Whether you manage a private residence, an apartment complex, a hospital, or an industrial site, regular water tank cleaning by a professional service like Raeli Hydro is one of the most cost‑effective ways to protect your water quality and your building’s infrastructure.

Borehole success rates in Turkana County vary widely depending on how and where the bores are drilled, but available assessments suggest that without proper hydro‑geophysical surveys, roughly one‑third of bores fail (dry or low‑yield), while well‑planned projects can reach 70–90% success.

What “success rate” means in Turkana

In Turkana, a “successful” borehole is usually one that:

• Finds water at a usable yield.

• Is drilled in a stable aquifer that does not dry up quickly each dry season.

Reports from NGOs and water‑resource studies note that before systematic surveys and modern logging, as few as half of the thousands of boreholes drilled in Turkana were functional, because many were placed in unsuitable zones or in shallow, highly saline layers.

Reported success‑rate ranges

• Unplanned / haphazard drilling
  Surveys of groundwater‑development practice in Turkana state that about two in three boreholes drilled without proper geophysical information turn out dry or under‑performing, implying a success rate around 30–40% when no pre‑drilling survey is done.

• With geophysical surveys and professional siting
  Where organisations use resistivity or VES‑based targeting, success rates are much higher. For example, Oxfam and similar partners report 70–80% successful bores in their focused Turkana projects.
  Some experienced drilling contractors working in Turkana, such as Raeli Hydro, quote internal success rates of about 90–98% when they control the survey and siting, although this reflects their own high‑standard practice rather than a county‑wide average.

Why the rate is not uniformly high

Several factors keep the overall success rate lower across the whole county:

• Drilling without surveys: Many bores are still sunk by small contractors or communities relying on “experience” rather than resistivity/VES, which increases dry‑hole risk.

• Over‑abstraction in hotspots: In areas with heavy groundwater use (e.g., oil‑field‑related abstraction in Lokichar basin), water levels drop, so some previously productive bores decline or fail.

• Mechanical and maintenance failures: Even successful bores often become non‑functional later due to pump failures, poor casing, or lack of maintenance, which distorts the long‑term “success” picture.

Practical takeaway for planning

If you are planning a borehole in Turkana:

• Treat 30–40% as a realistic worst‑case success rate if you skip a geophysical survey.

• Aim for 70–90% by working with a contractor who uses resistivity/VES and who has a documented track record in Turkana.

In short, the average borehole success rate in Turkana is roughly 30–40% when drilling is done without proper surveys, but can rise to 70–90% or higher when professional hydro‑geophysical siting is applied.

Borehole drilling in Turkana County is typically more expensive than in many other parts of Kenya because of a combination of logistical, geological, and operational factors that push the per‑metre rate higher.

Long distance and poor access

One of the biggest reasons drilling costs more in Turkana is distance and rough terrain. Many sites are far from major towns, with poor or unpaved roads, so rigs, fuel, and materials must cover long distances over difficult ground. This dramatically increases:

• Mobilisation and transport fees to move heavy drilling rigs and casing.

• Fuel and standby time because rigs move slowly and may need to wait for road conditions or security approval.

Several drilling‑cost tables for Kenya list Turkana with a per‑metre drilling range of about KSh 8,000–9,500, higher than softer‑soil counties like Machakos or Kitui, where the rate is closer to KSh 6,500–7,000 per metre.

Hard and deep‑rock geology

Turkana’s subsurface often includes hard rock, fractured formations, and deep aquifers, which slow down drilling and wear out equipment faster. In these conditions:

• Rigs must work longer hours to reach water, increasing labour and fuel costs.

• Drilling rigs and drill bits experience more wear, so contractors factor in higher per‑metre rates to cover repairs and replacements.

When the water table is deep (often 100–200 m or more), the bore must be drilled, cased, and tested over a much greater length, pushing the total project bill well above projects in shallow‑aquifer regions.

Remote‑site operational overhead

Drilling in remote Turkana locations introduces extra “hidden” costs that are smaller in urban counties:

• Crew and equipment standby charges while waiting for approvals, visas for security‑sensitive areas, or favourable weather.

• Local security and permits, especially near borders or oil‑exploration zones, which can delay schedules and add to daily costs.

• Logistics for water, power, and camping for the drilling team, since basic services are limited.

Many contractors treat these as part of the per‑metre rate or mobilisation fee, rather than listing them separately, so the headline price per metre already reflects the remote‑site premium.

Market‑driven per‑metre rates in Turkana

Price‑guides for Kenyan boreholes consistently show that Turkana sits at the upper end of the drilling‑cost spectrum:

This means that for the same depth, a borehole in Turkana will usually cost more than an equivalent bore elsewhere, even before adding pumps, tanks, and solar‑power systems.

How to manage costs in Turkana

Even though the baseline is higher, several steps can control the cost:

• Order a geophysical survey (e.g., resistivity) before drilling to avoid going much deeper than necessary.

• Request a detailed breakdown from at least two Turkana‑experienced contractors, including mobilisation, drilling, casing, and standby‑day charges.

• Plan for a complete system (pump, power, tank) in one budget so that “drilling only” quotes don’t later balloon when other components are added.

In short, borehole drilling in Turkana becomes more expensive mainly because of long‑haul logistics, hard/difficult rock, deeper aquifers, and higher standby/remote‑site overheads, which together justify the KSh 8,000–9,500 per‑metre band seen in market‑price tables.

PVC and steel casing are the two main options for boreholes in Kenya, and their costs differ significantly even though both serve the same core purpose: to prevent borehole collapse and contamination. In general, PVC casing is roughly 40–60% cheaper than steel casing per metre, but the right choice depends on geology, depth, and long‑term durability needs.

Per‑metre cost comparison

Recent market data and contractor quotes for Kenya show the following typical price ranges:

For a 100‑metre borehole, that means PVC casing usually adds about KSh 120,000–250,000, while steel can easily reach KSh 250,000–350,000 just for the casing material, before drilling, pumping, and tanking. This “PVC savings zone” is why many contractors quote PVC as the default choice for residential and low‑to‑medium‑depth projects.

Hidden cost differences

Beyond the sticker price per metre, other factors affect the total cost:

• Transport and handling: PVC is lighter and easier to move, reducing transport and labour charges, especially on rough or remote sites.

• Installation speed: PVC sections are simpler to push/assemble, cutting rig‑time and standby fees.

• Durability vs. corrosion: Steel provides superior strength in collapsing soils and high‑pressure zones, but it can rust over time if not properly protected; PVC is immune to corrosion but may creep or deform under extreme wall‑pressure.

Some contractors even recommend steel casing only for the unstable upper section (e.g., top 20–50 m in loose or collapsing soils) and PVC below, which can cut cost while still protecting the bore.

When to choose PVC vs steel

Here is a practical guideline used by Kenyan drilling firms:

Many drilling education pieces in Kenya note that about 70–80% of successful residential bores use PVC, precisely because it is cheaper and sufficient for most common geological conditions.

How to decide for your project

To get the best cost‑effective choice between PVC and steel casing in Kenya:

• Get a geological report or resistivity survey to know if you are in collapsing soils or deep‑rock zones.

• Ask for a breakdown of “PVC only”, “steel only”, and “steel upper section + PVC main column” in your quote so you see the real cost difference.

• Don’t automatically pick steel “just in case”; in many stable sites, PVC is engineering‑sound and far cheaper, while steel is only justified where the ground really demands it.

In short, PVC casing runs about KSh 1,200–2,500 per metre and steel about KSh 2,500–3,500 per metre in Kenya, so PVC is typically the more economical choice unless the geology or depth strongly favours steel.

Boreholes in Turkana County typically range from shallow to deep, depending on whether they target alluvial/lagga aquifers or deeper regional formations.

Typical depth range in Turkana

Studies and project reports show that borehole depths in Turkana vary roughly between 20 m and 200 m, with many community and household bores falling inside that band. Boreholes closer to seasonal rivers (lagga) and Lake Turkana are often shallower, sometimes under 50 m, while those further from known surface‑water features may need to be drilled to 100–200 m or more to reach stable, lower‑salinity aquifers.

Depth by location type

County‑level water‑resources assessments also note that some planned schemes target medium‑depth aquifers (35–80 m below ground level), especially where preliminary investigation data are available, and only deeper drilling (100+ m) is recommended where the shallow zone is saline or unreliable.

What “average” depth to plan for

If you are planning a borehole project in Turkana County, planners and drilling contractors often use an effective planning depth of about 100–150 m as a practical working average, assuming:

• You are not immediately on a known lagga or river‑alluvium belt.

• You want to tap reasonably stable groundwater with lower risk of drying in dry seasons.

• You accept higher cost and longer drilling time to secure a higher‑yield, longer‑life bore.

For a more precise figure, many water‑supply projects in Turkana design bores in the 120–180 m range when targeting deeper aquifers that can support schools, health centres, or small‑town reticulation.

Why depth varies so much

Several factors create this wide spread in required borehole depth:

• Distance from lagga or Lake Turkana: closer sites often produce shallow bores; inland sites need more depth.

• Groundwater quality: shallow aquifers near dry riverbeds can be saline or brackish, forcing deeper drilling for fresher water.

• Aquifer type: alluvial sands and gravels near lagga are shallow, whereas deeper sedimentary or fractured‑rock aquifers may need 100–200 m.

In practice, if you are developing land at some distance from rivers or lakes in Turkana County, it is reasonable to budget for a 100–150 m borehole as a working average, while still commissioning a pre‑drilling resistivity survey to confirm whether 80 m or 180 m is more appropriate for your specific site.