The quality of a borehole is largely determined by the competence and integrity of the contractor who drills it. Unlike a building or road, a borehole cannot be visually inspected after construction — what happens underground during drilling is largely inaccessible to later scrutiny. Selecting the right drilling contractor, and conducting thorough due diligence before awarding a contract, is therefore one of the highest-impact decisions in the entire project.
Why Contractor Selection Matters
Drilling is a technically demanding operation where shortcuts and poor practice have immediate and lasting consequences. An under-qualified or unscrupulous contractor may:
- Install inadequate or non-specification casing and screen to cut costs.
- Fail to properly grout the annular space, creating a pathway for surface contamination.
- Neglect or abbreviate borehole development, reducing long-term yield.
- Falsify drilling logs or pumping test data.
- Use recycled or substandard materials.
- Abandon a difficult hole without proper notification.
None of these failures may be immediately apparent — but all of them will manifest over time in poor water quality, declining yield, or premature borehole failure.
Defining the Prequalification Criteria
Before inviting tenders, define the minimum technical and financial criteria that a contractor must meet to be eligible. These typically include:
Technical Capacity
- Ownership or long-term access to drilling rigs of the specification required for the project geology and depth.
- A demonstrated track record of drilling comparable boreholes (depth, geology, diameter) in the target region.
- Qualified and experienced drilling supervisors and rig operators.
- Access to laboratory or field testing equipment required for development and pumping tests.
Regulatory Compliance
- Valid drilling contractor licence or registration with the relevant water authority (where required by law).
- Compliance with environmental and safety regulations.
- Valid insurance: public liability, employer’s liability, and equipment insurance at specified minimum cover levels.
Financial Standing
- Sufficient financial capacity to mobilise and sustain operations without advance payments becoming a cash flow problem.
- No record of insolvency, liquidation, or significant outstanding judgements.
- Bank reference or audited accounts confirming financial stability.
References and Track Record
- Contact details for at least three recent clients for whom similar work was completed.
- Willingness to allow inspection of past borehole completion reports and pumping test records.
The Tendering Process
A competitive tendering process achieves two objectives: it establishes a market-based price and provides a basis for assessing contractor capability. A well-run tender includes:
Tender Documents: The tender package should include a full project description, borehole design specifications, a priced bill of quantities, contract conditions, health and safety requirements, and reporting obligations. Ambiguity in tender documents invites claims and disputes later.
Pre-Bid Site Visit: A mandatory site visit allows contractors to assess access, local conditions, and any site-specific challenges. It ensures all bidders are pricing on the same basis.
Bid Evaluation: Price should not be the sole evaluation criterion. A two-envelope system — technical proposal evaluated first, then price — prevents a low-price offer from clouding judgement about technical capability. Award to the cheapest bidder without reference to technical merit is a common route to project failure.
Reference Checks and Due Diligence
Before awarding a contract, conduct thorough due diligence on the preferred bidder:
Reference Calls: Contact previous clients directly. Ask specifically about: were specifications met? Was work completed on time and within budget? Were drilling logs and test reports accurate and complete? Would they use the contractor again?
Licence Verification: Confirm the contractor’s drilling licence is current and in good standing with the issuing authority.
Equipment Inspection: Where possible, visit the contractor’s yard to verify that the rig to be used is in operational condition, not just listed on paper.
Subcontracting Arrangements: Clarify whether any part of the work will be subcontracted. Subcontracting key technical elements to unverified parties introduces risk that the main contractor assessment does not capture.
Red Flags to Watch For
During the selection process, be alert to the following warning signs:
- Unusually low prices that are inconsistent with market rates (typically more than 20% below the average of other bids).
- Vague or incomplete technical proposals with no specifics about method, materials, or timelines.
- Reluctance to provide references or permit inspection of past work.
- Requests for unusually large advance payments before mobilisation.
- No current insurance certificates or expired regulatory licences.
- Claims of capability in geological conditions or depths significantly beyond their documented experience.
Formalising the Selection
Once the preferred contractor is identified, the selection decision and rationale should be documented — including the scoring of technical and financial criteria — before contract negotiation begins. This transparency protects the client in the event of a challenge from unsuccessful bidders and creates an auditable record for donors, regulators, or oversight bodies.
