Is tap water safe in Vietnam? Ice, raw vegetables and where the real risk sits

This question arrives in two forms. One is sensible and worth answering properly. The other is a kind of anxiety that makes people miserable for a fortnight and does nothing measurable for their health. They are policing the wrong things.

The honest answer has three parts. Tap water is not drinking water here; the ice in a cafe almost certainly is. And the thing that most often makes visitors ill is neither. Nothing on this page diagnoses anything. If you are already unwell, the signs in the next section are the ones that matter.

When a stomach problem stops being a stomach problem

Most gut upsets settle on their own. Call 115 or go to the nearest hospital if you see any of the following, rather than waiting for it to pass:

• Vomit containing blood, or that looks like coffee grounds
• Severe pain locked into one spot in the abdomen, rather than general cramping
• A stiff abdomen that hurts to touch anywhere
• Confusion, or being unable to stay awake
• No urine at all for most of a day, with dizziness on standing
• A high fever alongside the diarrhoea, which in Vietnam needs a cause established rather than assumed
• In a small child: refusing every fluid, a sunken soft spot on the head, or no wet nappy for many hours

What comes out of the tap

Municipal supply in Vietnamese cities is treated and chlorinated, and it is not the same thing as an untreated well. The problem sits between the plant and your shower. Ageing distribution pipes, rooftop storage tanks that are cleaned on no fixed schedule, pressure drops that let groundwater in at joints, and buildings where the plumbing has been extended several times by several people.

So the official position and the practical one agree: do not drink it unboiled. Boiling for a minute at a rolling boil deals with the organisms that matter, which is why every hotel room has a kettle and why locals drink tea constantly. A filter jug improves taste and removes some contaminants but is not a substitute for boiling unless it is specifically rated for microbiological treatment.

Ice, and why it is usually not the villain

Ice gets blamed more than any other item. It deserves it least. Vietnam has a large commercial ice industry that makes ice from treated water in factories, delivers it in sealed bags, and supplies virtually every cafe and restaurant in every city. That ice arrives as clear cylinders with a hole through the middle, or as clear cubes. It is fine.

The ice to think twice about is cloudy, irregular, in broken chunks, or crushed from a block of unknown origin at a stall with no refrigeration. That is uncommon in cities and more plausible in a remote village or at a beach cart. The visual test is easy. Clear and uniform means a factory; cloudy and ragged means someone made it themselves.

The shaved ice in a dessert is the same question. Where it came from matters; the fact that it is ice does not.

Raw vegetables and the plate of herbs

This is a more genuine risk than ice, and it is also central to how the food works. A plate of raw herbs — perilla, mint, coriander, water spinach, sawtooth coriander — comes with half the dishes in the country, and the point of it is freshness.

The risk is not the leaf. It is the water it was rinsed in, and the hands that handled it. In a busy restaurant with high turnover, washed with treated water, it is routine and locals eat it at every meal. At a stall where a bucket of water sits in the sun being reused, it is a different proposition.

Two leafy things deserve particular care. Water spinach eaten raw, and other plants grown in standing water, which is where liver and intestinal flukes live. And bean sprouts, which are grown warm and wet and are a known vehicle in many countries. Both are fine cooked. That is what most Vietnamese dishes do anyway.

Fruit, juice and the blender

• Fruit you peel yourself is about as safe as food gets — bananas, mandarins, mangosteen, longan, rambutan, pomelo
• Pre-cut fruit sitting unchilled on a tray has been handled, cut on a board, and left at ambient temperature. That is three risks stacked
• Fresh juice pressed in front of you is usually fine. The questions are the ice, the water in the jug, and whether the blender was rinsed in clean water
• Sugarcane juice is pressed through a mangle that is hard to clean, which makes the turnover of the stall the thing that matters
• Fruit washed in tap water and handed to you wet is a small risk, and drying it with a clean tissue removes most of it
• Coconut water drunk straight from the nut is sealed by the fruit itself, and it rehydrates well

Teeth, showers and swimming pools

Brushing teeth with tap water is a judgement call rather than a rule. The volume swallowed is tiny, and plenty of long-term residents do it without consequence. If you have a sensitive gut, are travelling with a small child, or are in a building where the water smells or runs cloudy, use bottled or boiled water for the brush. It costs nothing and removes a variable.

Showering and washing are not a problem. The skin is a good barrier. Keep your mouth closed and do not drink in the shower, which sounds obvious and is exactly what people forget with children.

Pools are chlorinated and generally fine. Swallowing pool water repeatedly, which is mostly a children's problem, can cause a gut upset regardless of chlorine. Natural swimming is a different question. Still freshwater in warm climates carries its own risks, and an open wound belongs out of any water at all.

Street food is not the thing to be afraid of

The reflex is to assume that a plastic stool means risk and a tablecloth means safety. The evidence does not support that. A stall selling one dish to a hundred people a day cooks at high heat in front of you. Its stock turns over in hours. A quiet restaurant with a large menu has food sitting somewhere between the kitchen and the lunchtime that never came.

Useful signals: a queue, a short menu, cooking happening at the moment you order, food served hot rather than warm, and a cook who handles money and food with different hands. Unhelpful signals: air conditioning, a printed menu, and the price of the chair you are sitting on.

Two infections that use the same route

Worth knowing. Both are vaccine-preventable, and neither is obscure here. Hepatitis A travels by contaminated food and water. It incubates for weeks, and arrives as profound tiredness, nausea and then yellowing — long after the meal that caused it, which is why nobody ever identifies the source. Typhoid takes the same path and presents as a steadily climbing fever rather than a dramatic stomach upset.

Vaccination for both is recommended for most visitors to Vietnam, and the typhoid vaccine is partly rather than fully protective, which means the food and water habits still matter afterwards. Neither is a reason to be frightened of lunch. Both are a reason to see a travel clinic before you fly, and to take a fever here seriously rather than filing it under something I ate.

If you are staying for months

• Find out where your building's water tank is and when it was last cleaned. In older apartment blocks the answer is often illuminating
• An under-sink or counter-top filter rated for microbiological removal makes boiling unnecessary for drinking water and ends the plastic bottle problem
• Watch for plumbing work in the street outside. A pressure drop followed by cloudy water is a signal to boil everything for a few days
• Get the hepatitis A and typhoid vaccinations if you have not. Over months the exposure arithmetic changes
• Keep oral rehydration salts in the cupboard rather than buying them while unwell
• Mentioning a gut problem that has lasted more than a fortnight is worth doing, because parasites run on that timescale and they do not resolve by being ignored

The short version

Do not drink unboiled tap water. Do not worry about clear factory ice, which is nearly all of it. Be slightly careful with raw leaves at stalls that reuse rinsing water, and with pre-cut fruit left out in the heat. Eat the street food. And treat a fever with a stomach upset as something that needs a cause, not a diagnosis you make yourself.