Emergency Water: Drinking Safely in an Outage

A Johannesburg water outage can last a few hours or stretch into days. When the taps go dry, most households reach for whatever stored water they have — and the question that matters most is whether that water is actually safe to drink. This guide covers storage, treatment options and when boiling is warranted, without the marketing spin.

Why outage water safety deserves more attention than it usually gets

Johannesburg Water’s own audited figures put non-revenue water at 44.8% for 2024/25 — a number that reflects significant losses through ageing infrastructure. That same infrastructure affects water quality. During a pressure drop or pipe burst, contaminants can enter the reticulation system, meaning water that was clean before the outage may not be clean when supply resumes. This is not scaremongering; it is the reason municipalities sometimes issue boil-water notices after major supply interruptions.

The relevant quality benchmark for drinking water in South Africa is SANS 241 (2024 edition), published by the South African Bureau of Standards. Any water you drink during an outage — stored, treated or sourced alternatively — should ideally meet that standard. The practical reality is that you rarely have a lab on hand, so sensible precautions fill the gap.

Safe storage: the first line of defence

The simplest way to have safe emergency drinking water is to store clean municipal water before the outage happens. A few practical points:

• Use food-grade containers. Containers marked with recycling codes 1, 2 or 4 are generally considered food-safe. Avoid repurposing containers that held chemicals or non-food liquids.
• Keep containers sealed and out of sunlight. UV light and warmth encourage algae and bacterial growth.
• Rotation matters. Stored water does not have an indefinite shelf life once opened or repeatedly accessed. As a rough guide, sealed containers stored in cool, dark conditions are typically acceptable for several months, but confirm this with the container manufacturer’s guidance rather than relying on a single source.
• Quantity planning. South Africans use on average about 237 litres of water per person per day according to IWA Water Policy data — well above the world average of roughly 173 litres. Drinking and basic hygiene require a far smaller fraction of that, but it is worth knowing your household’s baseline when sizing storage.

For guidance on sizing tanks and organising home water storage more broadly, the WaterQuotes resilience and solutions blog covers practical options suited to Johannesburg conditions. A detailed look at container types, tank sizing and rotation schedules is available in our guide on how to store water for an outage.

When to boil, and when boiling is not enough

Boiling is effective against biological contaminants — bacteria, viruses and protozoa. Bringing water to a rolling boil for at least one minute is sufficient at Johannesburg’s altitude (you would need longer at significantly higher elevations, but Johannesburg does not reach the threshold where this matters for most residents).

Boiling is not effective against:

• Chemical contaminants (heavy metals, pesticides, industrial pollutants)
• Sediment or turbidity — filter first if water is visibly cloudy
• Salinity

If you suspect a chemical source of contamination — for instance, your water has an unusual smell beyond chlorine, or comes from a borehole near industrial land — boiling alone is insufficient. In those cases, the National Institute for Communicable Diseases (NICD) advises seeking guidance from your local health authority rather than attempting home treatment for chemical contamination.

The working principle is simple: test first, treat second. If you do not know the source, treat for biological risk at minimum, and avoid the water for drinking if chemical contamination is possible until you can confirm otherwise.

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Chemical treatment as a boiling alternative

When boiling is impractical — during load shedding, for instance, when you may have neither gas nor electricity — chemical treatment is a recognised alternative for biological disinfection.

Treatment method	Effective against biology?	Effective against chemicals?	Practical notes
Boiling (rolling, 1 min)	Yes	No	Requires heat source
Household bleach (unscented, 5% chlorine)	Yes (at correct dose)	No	Dose must be correct; taste may be noticeable
Water purification tablets	Yes (product-dependent)	No	Follow pack instructions precisely
Ceramic/activated carbon filter	Partial (depends on filter)	Partial (activated carbon)	Varies by product quality

For household bleach, the dosing guidance varies by chlorine concentration — check the label and follow the specific ratio. An incorrect dose is either ineffective or introduces its own risk. Purification tablets from a reputable pharmacy are a more controlled option for emergency use.

Neither chemical treatment nor basic filtration replaces proper water quality testing if you intend to use a non-municipal source regularly.

Borehole and rainwater: safe for drinking?

Some Johannesburg homeowners turn to boreholes or rainwater harvesting as backup supplies. Both can be suitable for various uses, but neither should be assumed safe for drinking without testing.

Borehole water quality in Johannesburg varies considerably depending on depth, geology and proximity to contamination sources. Typical complete borehole systems in Johannesburg run R40,000–R150,000, with most falling between R60,000 and R100,000 — a meaningful investment that should include a water quality test before the system is used for drinking. Borehole pumps typically cost R15,000–R35,000 installed, and should be sourced through a registered driller who can advise on local aquifer conditions.

Rainwater collected from roof surfaces picks up whatever is on that surface — bird droppings, dust, debris and whatever has settled in gutters. First-flush diverters reduce this, but do not eliminate it. Rainwater intended for drinking should be filtered and disinfected, and ideally tested.

The SANS 241 (2024 edition) standard is your reference point for what constitutes safe drinking water regardless of source.

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What to do when supply resumes

When municipal water returns after an extended outage, do not assume it is immediately safe to drink straight from the tap. Let the tap run for a minute or two to flush standing water from the pipes. If your municipality has issued a boil-water notice, follow it until it is lifted — these notices are issued based on actual testing, not precaution alone.

If your water has an unusual colour, smell or taste after supply resumes, report it to Johannesburg Water and avoid drinking it until the issue is resolved. Discolouration after a pipe repair is often rust or sediment disturbance rather than a health hazard, but it is worth waiting for it to clear and confirming with your municipality if it persists.

Emergency water safety does not require expensive equipment in most scenarios — it requires knowing your source, treating appropriately for what you know and what you do not, and keeping enough clean stored water on hand to cover the gap.