How deep does a borehole need to be to find water?

There is no single answer — depth depends entirely on local geology and where the water-bearing zone sits. In fractured-rock areas like much of Gauteng, productive fractures might be found anywhere from 30 metres to well over 100 metres down. A hydrogeological assessment or local driller knowledge will give you a more realistic expectation for your specific area than any general figure can.

Is borehole water safe to drink without treatment?

Not necessarily. Groundwater is naturally filtered by soil and rock, which removes many surface contaminants, but dissolved minerals, bacteria and other substances can still be present at levels that exceed SANS 241 (2024 edition) limits. Always have the water professionally tested before using it for drinking or cooking, and install appropriate treatment based on those actual results rather than assumptions.

How long does a borehole last?

A properly drilled and cased borehole can last several decades with reasonable care. The weak point is usually the pump, which is a mechanical component subject to wear and will need servicing or replacement over time. Casing and screen longevity depends on material choice and the corrosiveness of the local groundwater. Regular water-level monitoring helps you spot declining yield before it becomes a problem.

Can a borehole run dry?

Yes, particularly if the pump is sized above the borehole's sustainable yield, or if the aquifer is under stress from drought or heavy local extraction. A proper yield test before pump installation sets the right pump size to avoid over-pumping. A float switch or level sensor in the borehole will cut the pump automatically if water drops too low, protecting both the pump and the aquifer.

Do I need municipal permission to drill a borehole?

Requirements vary by municipality and water management area. In most parts of South Africa, groundwater use is regulated under the National Water Act, and you may need to register the borehole and, depending on volumes used, obtain a water use licence. Your installer should advise you on local requirements, and it is worth confirming with your municipality before drilling begins.

How Does a Borehole Work? Aquifers, Casing and Pumps Explained

Turning on a tap that draws from your own borehole feels straightforward — until something goes wrong and you realise you have no idea what is actually happening underground. This guide walks through every stage of a borehole system in plain language: where the water comes from, how the hole is kept open, and how the pump moves water to where you need it.

Where Does Borehole Water Come From?

All borehole water originates as rainfall. Some of that rain soaks into the ground rather than running off into rivers or evaporating. It percolates downward through soil and fractured rock until it reaches a zone where the pores and cracks in the rock are fully saturated. That saturated zone is called an aquifer.

South Africa has two broad aquifer types:

Porous aquifers — found in sedimentary areas where water fills the spaces between sand or gravel grains. These tend to deliver water more reliably and predictably.
Fractured-rock aquifers — found in granite, quartzite and other hard rocks. Water sits in cracks and joints. These are common across Gauteng and much of the highveld. Yields vary considerably depending on how well-fractured the rock is and whether your borehole actually intersects a productive fracture.

The depth to water varies enormously by location. If you want a local perspective, the piece on water table depth in Johannesburg gives useful context for Gauteng specifically, though the principles apply nationally.

Because groundwater moves slowly through rock, it is naturally filtered of many surface contaminants — but this does not mean it is automatically safe to drink. Dissolved minerals, bacteria and other contaminants can still be present. SANS 241 (2024 edition) is the South African standard that defines safe drinking-water quality, and any water intended for drinking should be tested against it.

How Is the Borehole Drilled?

A drilling rig uses either rotary percussion (a hammer bit that crushes rock) or rotary drilling (a rotating bit that grinds through softer formations). The drill cuts a hole — typically 110 mm to 165 mm in diameter for residential use — and the drilled material is flushed back to the surface with water or compressed air as the hole deepens.

The driller logs the material coming up: soil type, rock type, colour changes, the presence of water-bearing zones. This log becomes important later when deciding where to place the screen. For a closer look at the full drilling process, our borehole drilling overview covers what to expect from initial survey through to completion.

Casing and Screening: Keeping the Hole Open

Once the hole is drilled, it needs to be supported and protected. That is the job of the casing — a rigid pipe, usually uPVC or mild steel, that lines the borehole from the surface down to a point below the water table.

Casing serves several purposes:

Prevents the walls collapsing
Stops surface water and contaminants entering near the top
Provides a clean conduit for the pump and rising main

At the base of the casing, in the water-bearing zone, a screen is fitted. The screen is a slotted or perforated section that allows water to flow in while keeping sand and fine sediment out. Slot size is matched to the formation — too large and you get a silty pump; too small and you restrict flow unnecessarily.

A gravel pack is sometimes placed around the screen in sandy formations to improve filtration. In solid fractured rock, a gravel pack is generally not needed because the rock itself holds the hole open.

The borehole casing explained post goes into considerably more detail on material choices and installation standards if you want to dig deeper.

Yield Testing: Knowing What the Borehole Can Actually Deliver

Before any pump is installed permanently, a yield test should be carried out. This involves pumping the borehole at a controlled rate and measuring how quickly the water level drops and how long the borehole can sustain a given output.

Yield is typically expressed in litres per hour or litres per second. A borehole that looks good at first pump can sometimes recover slowly or dry up if pumped harder than the aquifer can sustain. Oversizing the pump relative to yield is one of the most common mistakes in residential borehole installations.

You can read more about what yield testing involves and why it matters in the borehole yield testing explained article.

If you are trying to work out whether a borehole makes sense for your property, comparing installer opinions side by side is the fastest way to cut through the uncertainty. Compare 3 free quotes — vetted installers, no obligation.

The Pump: Lifting Water to the Surface

Most residential boreholes use a submersible pump — an electric motor and pump unit sealed in a single housing, designed to operate while submerged in water. It sits on the rising main (the pipe running up the borehole) at a depth below the standing water level, typically at least a metre or two above the borehole bottom to avoid drawing in sediment.

The pump pushes water up the rising main rather than sucking it, which is why submersible pumps can operate at depths far beyond the roughly 7–8 metre practical limit of surface suction pumps.

Key pump considerations:

Factor	Why It Matters
Flow rate (l/hr)	Must match borehole yield — oversizing drains the borehole
Head pressure (metres)	Must overcome the depth plus any additional height to the tank
Power supply	Mains, solar or generator backup affects running costs and reliability
Control box / level switch	Protects the pump from running dry if the borehole is over-pumped

Pump costs vary with depth, brand and whether solar is involved. As a Johannesburg reference point, borehole pumps typically cost R15,000–R35,000 installed — prices elsewhere may differ, so get local quotes to confirm.

From Pump to Tap: Storage and Distribution

Water pumped from the borehole does not go straight to your taps in most domestic systems. It is stored in a tank — either a surface tank or a buried tank — and then a booster pump distributes it through your home at usable pressure.

This two-stage approach (borehole pump to tank, booster pump to taps) gives you several advantages:

You pump from the borehole at its sustainable yield rather than on demand, protecting the aquifer
You have a buffer if the borehole needs maintenance
The booster pump delivers consistent pressure regardless of how deep the borehole pump is

Tank sizing should reflect your household’s daily use and how long you want to go between pumping cycles. Most installers size tanks to hold at least one to two days of typical consumption.

Complete borehole systems — drilling, casing, pump, tank and distribution — are a meaningful capital investment. Using Johannesburg figures as a reference point, typical complete systems run R40,000–R150,000, with most residential installations falling between R60,000 and R100,000. Costs in other regions may be quite different, so treat those figures as context only.

Ready to find out what a system would cost for your specific property and location? Get your free installer quotes — up to three vetted professionals, no obligation.

Water Quality and Treatment

Groundwater quality depends on the geology the water has passed through and what human activities exist above the aquifer. Common issues include high iron content, manganese, hardness, nitrates or, in some areas, microbial contamination.

Testing is not optional if the water will be used for drinking or food preparation. A basic potable-water test panel checks the main parameters against SANS 241 (2024 edition). Depending on results, treatment might range from a simple UV steriliser to an iron-removal filter or reverse osmosis unit.

The important principle: drill first, test the water, then design treatment around what the test actually shows — rather than guessing and over-treating or under-treating.

Putting It All Together

A borehole system is essentially a chain: rainfall recharges an aquifer, drilling and casing create a safe access point, a yield test confirms what the aquifer can sustainably deliver, a submersible pump lifts the water, and a storage-and-distribution system makes it usable at the tap. Every link in that chain needs to be properly specified for the system to work reliably over the long term. Understanding how each part functions puts you in a much stronger position when talking to drillers and installers — and when comparing what different quotes are actually offering you.