Borehole Water Testing
Cape Town

Borehole water testing is about quality, not quantity. It answers a completely different question from yield testing: not how much water you have, but what is actually in it.

The two are unrelated. A borehole with an excellent yield can produce water that needs substantial treatment, and a modest one can produce water that needs almost none. You cannot infer quality from flow, from clarity, from taste, or from what the neighbours say about their borehole.

This matters because the intended use sets the standard. Water that is entirely fine for irrigating a lawn may be unsuitable for filling a pool, feeding a boiler or drinking. Testing tells you which category your water falls into.

Why Borehole Water Is Not Automatically Safe to Drink

Groundwater is filtered by its passage through the ground, and it is often of good quality. But that same passage dissolves minerals from the rock it moves through, and the aquifer can be affected by what happens at the surface above it.

Two broad categories of concern arise, and they behave very differently:

Naturally occurring	Introduced from surface or human activity
Dissolved minerals picked up from the rock - iron, manganese, calcium, magnesium, fluoride, sodium and chloride.	Bacterial contamination from septic tanks, soakaways, sewer leaks, livestock or surface runoff entering the borehole.
Generally stable over time, changing slowly if at all.	Can appear suddenly and vary with rainfall, which is why a single clean result is not a permanent guarantee.
Affects taste, staining, scaling and, at certain concentrations, health.	Primarily a health concern, and the reason microbiological testing matters most.
Addressed by filtration, oxidation, softening or membrane treatment.	Addressed by disinfection, and by finding and eliminating the pathway allowing contamination in.

In coastal areas there is a third consideration - salinity, where over-abstraction near the coast can draw saline water toward a borehole. That shows up in the chemistry as elevated conductivity, chloride and sodium.

What Gets Tested

South African drinking water quality is assessed against SANS 241, which sets limits across several groups of parameters. A typical borehole analysis covers:

Microbiological

• E. coli - the key indicator of faecal contamination and the single most important health parameter
• Total coliforms - a broader indicator of contamination or ingress into the borehole
• Heterotrophic plate count - general bacterial load, useful context alongside the above

Physical and general chemistry

• pH - affects corrosion, scaling and how well treatment processes work
• Electrical conductivity and total dissolved solids - overall mineral load, and the first indicator of salinity
• Turbidity - suspended material, which interferes with disinfection and clogs filtration
• Hardness - calcium and magnesium, which drive scaling in pipes, geysers and appliances

Chemical parameters of particular interest

• Iron and manganese - very common in local groundwater. Cause reddish-brown or black staining on laundry, sanitaryware and paving, and can foul irrigation emitters
• Nitrate - associated with agricultural activity and sewage. A significant health parameter, particularly for infants
• Fluoride - naturally occurring in some formations, with both a deficiency and an excess concern
• Chloride and sodium - taste and salinity indicators, and important for irrigation of sensitive plants
• Sulphate - taste and, at higher levels, laxative effects
• Heavy metals where local geology or land use gives cause for concern

Not every borehole needs every parameter tested. The sensible approach is a core analysis covering microbiological and general chemistry, extended where the geology, the surroundings or the intended use suggest specific risks.

Sampling Correctly

A laboratory result is only as good as the sample. Poor sampling produces misleading results in both directions - false contamination from a dirty tap, or a falsely clean result from water that has been standing.

1. 1Use sterile containers supplied by the laboratory for microbiological samples. A rinsed bottle from the kitchen is not adequate.
2. 2Pump before sampling. The borehole should run long enough to clear water standing in the casing and pipework, so you are sampling formation water rather than what has been sitting in the system.
3. 3Sample from the right point. Usually directly at the borehole discharge, before any storage or treatment, so you are testing the raw water. Sampling after a tank tells you about the tank as much as the borehole.
4. 4Do not contaminate the sample - clean the sampling point, avoid touching the inside of the bottle or cap, and fill according to the laboratory's instructions.
5. 5Keep samples cool and deliver promptly. Microbiological samples in particular deteriorate, and a delayed sample can give a meaningless result.
6. 6Record the details - date, time, sampling point, how long the borehole ran beforehand, and any recent rainfall.

Use a laboratory with appropriate accreditation for the parameters being tested. Home test strips have their uses for rough monitoring of a single parameter, but they are not a substitute for a laboratory analysis when you are making treatment decisions.

Reading Your Results

A laboratory report lists measured values against reference limits. What it does not usually tell you is what to do about them. Broadly:

What the result shows	What it typically points to
E. coli or coliforms present	Contamination is entering the borehole. Disinfection treats the symptom, but the pathway must be found and closed - often a defective sanitary seal, damaged casing, or a nearby septic or sewer source. Retest after remedial work.
Elevated iron or manganese	Staining and taste rather than an acute health issue at typical levels, but a persistent nuisance. Usually addressed by oxidation followed by filtration.
High hardness	Scaling in geysers, kettles, pipework and irrigation emitters. Softening is an option where the use justifies it.
High conductivity, chloride and sodium	Elevated salinity. Relevant to taste, to irrigation of sensitive plants, and to corrosion. Membrane treatment is the usual route but it is costly and produces a reject stream.
Elevated nitrate	A genuine health parameter, particularly for infants. Points to surface influence such as agriculture or sewage, and needs specific treatment rather than general filtration.
High turbidity or sand	Suspended material. Sometimes a treatment matter, but persistent sand more often indicates a borehole construction or development issue - see rehabilitation.
All parameters within limits	Good news, but not permanent. Quality can change, particularly microbiologically, so periodic retesting is still worthwhile.

Treatment selection follows from these results and nothing else. Fitting a filtration system before testing means guessing at which problem you are solving. The borehole filtration systems page covers how each result translates into a treatment approach.

How Often Should You Retest?

Chemistry is fairly stable and changes slowly. Microbiological quality can change quickly, which is why the two are treated differently:

• Test a new borehole before it is put into service, and before any treatment is specified
• Retest microbiological parameters periodically where the water is used for drinking or food preparation
• Retest after heavy rainfall or flooding, which can mobilise surface contamination into an aquifer
• Retest after any work on the borehole, pump or headworks that broke the seal
• Retest if the water changes - in taste, smell, colour, or if it starts staining
• Retest if a potential contamination source appears nearby, such as new septic infrastructure
• Retest if the intended use changes, for instance from garden irrigation to household supply

Related Borehole Services

Water quality is decided by the aquifer and by how well the borehole is sealed against surface contamination, which is a construction question - see Borehole Drilling Cape Town for how casing and the sanitary seal keep shallow contaminated water out of the supply.

What Borehole Water Testing Costs

Laboratory cost tracks the number of parameters analysed. Tell the lab what the water is for so the panel is relevant - a full potability suite is wasted money if the water is going on a lawn.

Item	Indicative range	What moves it
Basic microbiological screen	R450 – R1,200	E. coli and total coliforms. The minimum where anyone might drink the water.
Standard SANS 241 domestic panel	R1,200 – R3,500	Microbiological plus general chemistry, iron, manganese, nitrate and the common parameters.
Extended analysis with metals	R3,500 – R8,000	Added where geology or nearby land use gives specific cause for concern.
Irrigation suitability panel	R1,500 – R4,000	Salinity, sodium adsorption ratio, chloride and boron rather than the potability parameters.
Sampling attendance	R500 – R1,500	Often waived if combined with a yield test or service visit.
Annual retest	R1,200 – R3,500	Worth budgeting where the water is used indoors.

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