Unused Boreholes: Decommissioning and Safety

An old borehole sitting unused at the back of a Johannesburg property might seem harmless. It is not. An open or poorly capped borehole acts as a direct conduit between the surface and the aquifer below — surface runoff, garden chemicals, and sewage can travel straight down into groundwater that other households may be drawing on. Beyond the environmental risk, an unsealed shaft is a physical danger and, under South African water law, a liability that sits with the property owner.

This article explains what proper borehole decommissioning involves, why it matters in a city already under water stress, and how to find a qualified contractor to do the work correctly.

Why abandoned boreholes are a genuine problem

Johannesburg sits above several interconnected aquifer systems. Contamination introduced through one opening can migrate laterally and affect boreholes some distance away. The Department of Water and Sanitation (DWS) recognises this: the National Water Act requires that any water use installation be maintained so that it does not cause pollution, and a borehole that has been drilled is considered an installation regardless of whether it is still in use.

Aquifer contamination is also cumulative and slow to reverse. Once pollutants enter a confined or semi-confined aquifer, remediation is technically difficult and extremely expensive. A property owner who leaves a borehole open and can be shown to have allowed contamination could face liability under both water law and common law nuisance principles — though the specifics depend on circumstances and you should seek legal advice on your own situation.

There is also a straightforward safety concern: an uncapped borehole shaft, particularly one with a wide casing or a damaged surface seal, is a fall hazard for children and animals.

What the law says

The National Water Act 36 of 1998, administered by DWS (www.dws.gov.za), governs groundwater use and protection. While the Act does not prescribe a single decommissioning standard in plain prescriptive language, it places a general duty of care on water-use licence holders and property owners. Local municipalities and the Groundwater Division (gwd.org.za) publish guidance that fills in the practical detail.

If your borehole was registered — which it should have been at the time of drilling — that registration creates a paper trail. Decommissioning should also be reported to the relevant authority so the record can be updated. Leaving a registered borehole as “active” when it is abandoned in practice creates administrative inconsistency that can complicate property sales and estate transfers.

For context on the broader registration and legal framework, the borehole drilling guide on this site covers what owners need to know before and after drilling.

What proper decommissioning actually involves

Decommissioning is not the same as simply pulling the pump out and throwing a concrete slab over the top. A surface cap alone does not prevent contamination through the annular space around the casing or through a corroded casing that has partially collapsed.

A properly decommissioned borehole typically involves:

Step	Purpose
Remove all downhole equipment	Pump, rising main, cables, any obstructions removed to allow grouting access
Video or physical inspection	Assess casing condition, depth, and any collapsed sections
Disinfection	Chlorination or similar treatment of the water column before sealing
Bottom-up grouting	Cement-bentonite grout pumped in from the bottom upward, displacing water rather than simply poured from the top — the critical step
Surface completion	Casing cut to below ground level, surface seal formed, site restored

The bottom-up grouting step is the one most often skipped by unqualified operators, and it is the step that actually prevents contamination pathways. Grout poured from the top channelling down the outside of the casing does not achieve a seal. Insist on a method statement from any contractor before work starts.

Because the job involves downhole equipment and grouting materials, it should only be done by a driller registered with the relevant professional body. If you are unsure whether your existing borehole is candidates for revival rather than sealing — particularly if it was drilled some years ago and is simply unused — it is worth reading this comparison of new versus revived boreholes before committing to decommissioning.

How to find a qualified contractor and what to expect to pay

Use a contractor who is registered with the DWS as a Water Use Licence applicant driller, or who works under one. Ask for their registration number and verify it. Request a written method statement specifying the grouting approach, the materials to be used, and how the decommissioning will be documented and reported.

Cost for decommissioning varies considerably depending on borehole depth, casing diameter, condition, and accessibility. As a rough guide, straightforward decommissioning of a shallow domestic borehole in Johannesburg might fall in the range of R8,000–R25,000, though complex jobs with significant depth or difficult access can run higher — confirm via quotes for your specific situation.

For guidance on how to read and compare contractor quotes properly, this article on comparing water quotes is worth reviewing before you accept any proposal.

Getting decommissioning quotes from a single source is a poor basis for a decision. Request 3 free quotes from vetted installers — no obligation, and you'll have a basis for comparison.

What if you are not sure whether the borehole is actually dead?

Some boreholes are abandoned simply because the pump failed or because the owner moved in after the system was last used. Before committing to decommissioning, it is reasonable to have the borehole professionally assessed: a water level measurement and a basic water quality test will tell you whether the aquifer is still productive and whether the water is within acceptable parameters under SANS 241 (2024 edition), the South African drinking-water quality standard.

If the borehole is viable and the property could use the supply — particularly given that Johannesburg Water’s own figures show non-revenue water losses of 44.8% in 2024/25, indicating systemic pressure on the municipal network — reviving the borehole may be more sensible than sealing it. The decision should be based on test results, not assumption.

That said, if the casing has collapsed, if the borehole has been open and unprotected for years, or if there is visible surface contamination nearby, decommissioning is almost certainly the right call.

Selling a property with an old borehole

This is where decommissioning or revival becomes a practical financial matter. Conveyancers and buyers are increasingly asking about borehole status during property transfers. An undisclosed, unregistered, or abandoned borehole discovered during due diligence can delay a sale and create disclosure disputes. Some buyers will view a documented, properly decommissioned borehole as straightforward; an unknown open shaft is a different matter entirely.

If you are preparing a property for sale and there is an unused borehole on site, address it — either commission a proper assessment and revival, or have it decommissioned and documented — before listing. The paperwork from a registered contractor showing proper sealing is a clean disclosure.

Whether you're reviving, decommissioning, or assessing an old borehole, qualified opinions matter. Compare quotes from registered borehole contractors — vetted, no-obligation.

The short version

An unused borehole is not a neutral feature on your property. It is either a resource worth recovering, or a hazard worth eliminating properly. Half-measures — a loose cap, an unplugged casing, a pump removed but the hole left open — do not constitute decommissioning and do not remove your liability.

Proper sealing, done by a registered contractor using bottom-up grouting, documented and reported to the appropriate authority, is the only outcome that actually closes the matter. For most Johannesburg homeowners, the cost is a one-time expense that eliminates ongoing risk — environmental, legal, and physical.