Borehole Pump Installation Step by Step: Setting Depth, Cabling and Commissioning

A borehole is only useful once the pump is in and working correctly. The installation process looks straightforward on paper — lower the pump, connect the water pipe and cable, wire the box — but each step has details that determine whether the pump lasts five years or fifteen. This article walks through what a competent installer actually does, so you know what to expect and what questions to ask.

Why Setting Depth Matters More Than Most People Realise

The pump must sit below the dynamic water level — the level the water drops to when the pump is running, not just the standing (static) level measured at rest. Set the pump too high and it runs dry during peak demand, burning out the motor. Set it too deep and you may pull fine sediment into the impeller or exceed the pump’s pressure rating.

A proper hydrogeological report or a yield test conducted after drilling will tell the installer where the dynamic level stabilises under sustained pumping. As a rule of thumb, installers typically aim for the pump to sit at least 10–20 metres below the dynamic level to provide a working buffer, though the actual figure depends on the aquifer’s recovery rate and the borehole’s total depth. Never accept a setting depth chosen without reference to a yield test — it is guesswork.

If you want to understand the full chain from drilling to pump selection before the installation day arrives, the WaterQuotes borehole drilling guide covers the earlier stages in detail.

Assembling the Rising Main

The rising main is the pipe that carries water from the pump to the surface. Most residential installations in South Africa use uPVC or HDPE pressure pipe rated to the pump’s maximum head. Sections are typically screwed or solvent-welded together as the pump is lowered, with each joint checked before the next section goes in.

Pipe diameter is matched to flow rate: undersized pipe wastes energy through friction loss; oversized pipe adds unnecessary weight and cost. Your installer should show you the hydraulic calculation or at least be able to explain the logic. A check valve is normally fitted at or just above the pump outlet to hold the water column when the pump stops, preventing water hammer and reducing start-up stress.

Cable Selection and the Splice

Submersible pumps run on flat or round submersible cable — not ordinary building wire. The cable must be rated for continuous submersion, sized for the pump’s current draw plus voltage drop over the run length, and compliant with SANS wiring standards. Undersized cable causes overheating; cable that is not rated for wet conditions deteriorates and can create a shock hazard.

The splice — the join between the pump’s factory lead and the surface cable — is a critical point. A properly made splice uses a waterproof heat-shrink kit designed for submersible applications, not tape or silicone. Many pump manufacturers will void their warranty if a splice fails for want of a proper kit. Ask your installer to show you the splice before the pump goes down; once it is underground it cannot be easily inspected.

For a closer look at how the control box interacts with the pump motor and cable, this explanation of borehole pump control boxes is worth reading before your installation day.

The Safety Rope: Simple but Non-Negotiable

A stainless-steel safety rope (or occasionally a rated polypropylene rope) is attached to the pump and anchored at the wellhead. Its sole job is to hold the pump if the rising main joints fail or the pipe pulls apart under load. Without it, a pump that separates from its pipe drops to the bottom of the borehole and becomes effectively irretrievable — a very expensive outcome.

The rope runs alongside the rising main, attached at intervals with cable ties or saddle clips, and should be rated to at least twice the combined weight of the pump, motor and full pipe column. This is a cheap component relative to the rest of the system; there is no good reason to skip it.

Setting depth, cable spec and splice quality vary significantly between installers. Compare 3 free quotes — vetted installers, no obligation.

Wellhead Completion and Cable Entry

Once the pump is at depth and the rising main reaches the surface, the wellhead is sealed. A proper wellhead cap or sanitary seal keeps surface water, insects and debris out of the borehole — open or poorly sealed boreholes are a common source of bacteriological contamination. The cable exits through a watertight gland, not simply draped over the casing lip.

From the wellhead, the rising main connects to the distribution pipework: typically a pressure tank, isolating valve and non-return valve arrangement. The cable runs in conduit to the control box, which should be mounted in a weatherproof enclosure, out of direct sunlight where possible.

Control Box Wiring and Electrical Compliance

The control box houses the motor starter, capacitor (on single-phase systems), overload protection and, on better installations, a dry-run protection relay that cuts power if the pump loses prime. All electrical work must comply with SANS 10142-1, the South African standard for wiring of premises, and the installation must be signed off by a registered electrician who issues a Certificate of Compliance (CoC). The Department of Labour’s regulations make clear that electrical installations require this certification — it is not optional and your insurer may decline a claim without it.

If you are choosing between installers, understanding what to look for in a borehole pump installer covers the licensing and compliance questions you should ask. And for a breakdown of what the pump component itself is likely to cost before commissioning, borehole pump installation costs gives useful reference figures for the Johannesburg market, which you can use as a starting point when getting quotes nationally.

The First Test Run and Commissioning Checks

Commissioning is the stage where everything is verified under real operating conditions. A methodical installer will work through a checklist that typically includes:

Check	What it confirms
Static and pumping water levels	Pump is set correctly; yield is as expected
Flow rate at surface	Matches pump curve for the setting depth
Operating pressure	Within design range; no pipe leaks
Motor current draw	Within nameplate rating; cable and starter are correct
Dry-run protection test	Relay or float switch cuts power as designed
Water quality visual check	No excessive turbidity after purging

After the initial purge — running the pump to clear drilling debris and disturbed sediment — the installer should take a sample for laboratory testing before you connect to household supply. SANS 241 (2024 edition) is the South African drinking-water quality standard; compliance with it requires an accredited laboratory result, not a visual check or a basic field kit. If the water will be used for drinking, always test first and treat second.

Typical complete borehole systems in Johannesburg run R40,000–R150,000, with most falling between R60,000 and R100,000; the pump and its installation typically accounts for R15,000–R35,000 of that. These are Johannesburg reference figures — costs elsewhere in South Africa will differ and you should confirm via quotes from local installers.

Ready to get real numbers for your site? Get matched with vetted installers — three quotes, no obligation, no cold calls from unvetted contractors.

What Can Go Wrong — and How to Protect Yourself

The most common installation failures are: pump set above the dynamic water level (dry running), undersized or non-submersible cable (overheating or shock hazard), an inadequate splice (water ingress to the cable, motor failure), and no electrical CoC (compliance and insurance risk). A missing safety rope is less common but results in an unrecoverable pump when anything else goes wrong.

The best protection is straightforward: use an installer who pulls a permit where required, issues a CoC, provides a written commissioning report, and offers at least a workmanship warranty on the installation separate from the pump manufacturer’s product warranty. Ask for all of this in writing before work starts, not after.