Safe Drinking Water for Babies and Formula

Preparing infant formula is one of the moments when water quality moves from background concern to front-of-mind urgency. The stakes are real: babies’ immune and digestive systems are not yet equipped to handle the contaminants that an adult body might cope with, and formula concentrate reconstituted with compromised water carries that risk directly. This guide sets out what the standards say, where Johannesburg-specific conditions add complexity, and which precautions are proportionate rather than alarmist.

What the standard actually says

South Africa’s drinking-water quality benchmark is SANS 241, maintained by the South African Bureau of Standards (SABS). The 2024 edition covers microbiological limits (including E. coli and total coliforms), chemical parameters such as nitrates and heavy metals, and physical properties like turbidity and pH. Water leaving a municipal treatment works is required to comply with SANS 241 before distribution. Compliance at the tap, however, depends on the condition of the entire distribution network between the works and your home — and that network is where variability enters.

SANS 241 is the baseline. It does not specifically address infant vulnerability beyond general population safety, so paediatric guidance from health authorities typically recommends additional precautions for young babies regardless of whether tap water formally meets the standard.

Why Johannesburg conditions deserve extra attention

Johannesburg Water’s own audited figures show non-revenue water of 44.8% for 2024/25 — a figure that reflects significant losses through leaks, pipe bursts and ageing infrastructure. Leaking mains can, under certain pressure conditions, allow contamination ingress even when water leaving the treatment works is compliant. The city’s reservoir system holds roughly 27 hours of citywide storage buffer, which means supply interruptions are not unusual, and any interruption typically triggers water being drawn from storage tanks at property level.

Storage tanks — JoJo tanks, steel tanks, or underground cisterns — introduce their own contamination risks if not cleaned and covered correctly. Sediment, algal growth, and bacterial proliferation are all possible in a tank that has not been serviced. If your home or complex relies on a storage tank as the primary supply point, you are not drawing directly from a compliant municipal source; you are drawing from water that may have sat for hours or days.

Borehole and rainwater: a higher bar

Borehole water in Johannesburg and its surrounds is not treated to any standard before it reaches your tap. Nitrate levels, bacterial contamination, and naturally occurring minerals vary considerably depending on the geology and proximity to any pollution sources. The same applies to rainwater harvesting. If your household uses borehole or harvested rainwater — whether as a primary source or a backup — it should be tested by an accredited laboratory before being used for any infant feeding purpose, and ideally retested seasonally. This is a straightforward precaution, not an extreme one.

For broader context on what treatment options exist and how they compare, the water filtration guide on this site covers the main technologies — reverse osmosis, ultrafiltration, activated carbon, and UV — with honest notes on what each does and does not remove.

Boiling: still useful, not a complete solution

Boiling water for at least one minute kills microbiological contaminants — bacteria, viruses, and protozoa — and is the most accessible precaution available to any Johannesburg household. The recommendation to use freshly boiled (and cooled) water for infant formula is based on this microbiological benefit.

Boiling does not, however, remove chemical contaminants such as nitrates, heavy metals like lead, or chlorination by-products. If anything, boiling concentrates dissolved solids slightly because water evaporates. This means boiling alone is not a complete answer if your concern is chemical rather than microbiological contamination. Where chemical risk is present — borehole water, old plumbing with lead solder joints, or post-interruption supply — filtration is more appropriate than boiling for those specific parameters.

If you're unsure whether your water is appropriate for infant formula, getting a system assessed costs nothing upfront. Compare 3 free quotes — vetted installers, no obligation.

Filtration options worth considering

Not every filter is appropriate for infant use. The key questions are what the filter is certified to remove and whether it introduces any risk of its own (for example, a poorly maintained filter can harbour bacteria).

Reverse osmosis (RO) systems remove a broad range of contaminants including nitrates, heavy metals, and most microbiological risks. They produce very low total dissolved solids (TDS) water, which some paediatric guidance treats with caution for exclusive use, though formula powder itself adds mineral content. RO systems require regular membrane and pre-filter changes.

Ultrafiltration (UF) removes bacteria and particulates but does not remove dissolved chemicals or nitrates. More useful for microbiological concerns than chemical ones.

Activated carbon reduces chlorine, some by-products, and taste/odour compounds. It does not reliably remove nitrates, heavy metals, or bacteria.

UV sterilisation is effective against microbiological contamination but removes nothing chemical and requires clear (low turbidity) water to work well.

In practice, a well-maintained RO system with a pre-filter stage is the option most households choose when they want broad coverage for infant use. As a rough guide, under-counter RO units typically cost R8,000–R20,000 installed — confirm pricing via quotes, as costs vary considerably by brand and local installer.

Lead and old plumbing: a specific risk to check

Older Johannesburg homes — particularly those built before the 1970s — may have plumbing that includes lead solder or lead-containing fittings. Lead leaches into water that sits in pipes overnight or during low-flow periods, and it is not detectable by taste or smell. The National Institute for Communicable Diseases (NICD) recognises lead as a significant childhood health concern with no safe level of exposure established for infants.

If your home is older and you have not had your water tested for lead, running the tap for 30–60 seconds before drawing water for formula is a simple interim measure. An accredited laboratory test for heavy metals, including lead, gives you a factual baseline to work from rather than guessing.

Water quality concerns for infants are worth acting on rather than hoping for the best — a filtration assessment is a practical first step. Get free quotes from vetted installers and find out what your home specifically needs.

A proportionate approach

For most Johannesburg households on direct municipal supply with no storage tank, no borehole, and reasonably modern plumbing, boiling water before making formula is a sensible and sufficient everyday precaution. If any of the following apply, the bar moves higher and professional assessment is worthwhile: you use a storage tank, you are on borehole or rainwater, your home is older and has not had a lead test, or you have experienced a recent pipe burst or supply interruption to your street. Test first, treat second — that principle holds regardless of which option you are considering.