Can You Drink the Water on a Nepal Trek?

No. Not from the tap, not from the stream, not from the teahouse kitchen unless it has been boiled or treated. This is the single most important health rule for trekking in Nepal, and the one that catches people out every season.

I have seen fit, prepared trekkers brought down by a glass of untreated water on day two. Not altitude, not exhaustion — a stomach bug that kept them in a teahouse bathroom for 36 hours while their group walked on without them. It is completely preventable, and yet someone on almost every trek learns this lesson the hard way.

What Are Your Options?

Bottled water: Available at every teahouse from Lukla to Gorak Shep. A 1-litre bottle costs 100 to 300 NPR at lower elevations, rising to 400 to 600 NPR above 4,000m. It works, it is safe, and it is the easiest option. The problem: plastic. A 12-day trek generates 30 to 40 empty plastic bottles per person. The waste stays in the mountains because there is no recycling infrastructure above Namche. If you care about the environment you are walking through, bottled water is the worst choice.

Boiled water: Teahouses will fill your bottle with boiled water for 50 to 200 NPR. This is safe as long as the water reached a full rolling boil. At altitude, water boils at a lower temperature (about 85°C at 5,000m), which is still hot enough to kill most pathogens but takes slightly longer. The downside: you need to wait for it to cool before drinking, and some teahouses do not boil it properly — they warm it and call it boiled.

Purification tablets: Chlorine dioxide tablets (Aquamira, Katadyn Micropur, or Potable Aqua) kill bacteria, viruses, and protozoa in untreated water. Drop a tablet in your bottle, wait 30 minutes (some brands say 15, but 30 is safer), and drink. Cheap, lightweight, no batteries, no moving parts. The taste is slightly chemical — adding a flavoured electrolyte sachet masks it completely.

SteriPEN or UV treatment: Battery-powered UV light that kills pathogens in 60 to 90 seconds. Faster than tablets, no chemical taste. The downsides: batteries die in the cold (carry spares in your jacket pocket), the device can break (bring tablets as backup), and it does not work in cloudy or sediment-heavy water (filter first or let particles settle).

Pump or squeeze filters: Sawyer Squeeze, Katadyn BeFree, or similar filters remove bacteria and protozoa but NOT viruses. For Nepal, this matters, viral gastroenteritis is common. Use a filter combined with purification tablets if you want belt-and-braces safety. A filter alone is not enough.

Safe Water Stations: Some villages on the EBC and Annapurna routes have installed refill stations that sell UV-treated water for 50 to 100 NPR per litre. Look for the blue "Safe Water" signs. These are the best option where available, cheap, safe, and zero plastic waste.

What I Actually Carry

Two 1-litre Nalgene bottles. A pack of chlorine dioxide tablets. And I refill at Safe Water Stations when they are available, boiled water when they are not, and tablets when I fill from a tap or stream.

I stopped buying bottled water three years ago. The tablets cost about $10 for a pack of 30, which covers an entire trek. The environmental difference is real, 30 fewer plastic bottles on the mountain per person, per trek.

How Much Water Should You Drink?

Three to four litres per day above 3,000m. That includes tea, soup, and any other liquid. Most trekkers drink about half what they should because cold weather suppresses thirst and the water is not always convenient to access.

Dehydration at altitude mimics altitude sickness symptoms, headache, fatigue, nausea, dizziness. Before you assume it is AMS, drink a litre of water and wait an hour. Half the time, the headache goes away.

Our guides remind trekkers to drink at every rest stop. It sounds annoying until day three when you realise the trekkers who are drinking are the ones who feel good, and the ones who are not drinking are the ones lying down with headaches.

What About Teahouse Tea and Coffee?

Tea is safe, the water has been boiled. Black tea, milk tea (chiya), and lemon-ginger-honey tea are all good options and count towards your daily fluid intake. Tea is also warm, which matters when you are sitting in a 5°C dining room at 4,400m.

Coffee is safe but risky for a different reason: caffeine is a diuretic at altitude. It makes you urinate more, which dehydrates you, which worsens altitude symptoms. One cup in the morning is fine. Three cups is asking for a headache by 2pm.

The best hot drink at altitude: lemon-ginger-honey tea. Hydrating, warming, settles the stomach, and every teahouse makes it. Our guides drink it constantly. There is a reason.

Can You Fill Up From Streams?

Technically yes, with treatment. Mountain streams above 4,000m look crystal clear, and many trekkers assume clear means clean. It does not. Yak dung, human waste from settlements upstream, and agricultural runoff all contaminate mountain water that looks perfectly clean.

If you fill from a stream: use purification tablets AND wait the full treatment time. Do not drink untreated stream water at any altitude in Nepal. The consequences, giardia, cryptosporidium, or bacterial dysentery — will ruin your trek far more effectively than altitude ever will.

What If You Get Sick Anyway?

Oral rehydration salts (ORS) are the first response. Our guides carry them. Mix one sachet with a litre of treated water and sip it slowly. This replaces the fluids and electrolytes you are losing and prevents the dehydration that makes stomach bugs dangerous at altitude.

If symptoms last more than 24 hours, or if you have a fever above 38.5°C, blood in your stool, or cannot keep fluids down: tell your guide immediately. These are signs of something more serious than a simple stomach upset, and you may need to descend to a clinic. There are basic health posts at Namche, Pheriche (on the EBC route), and Manang (Annapurna Circuit).

Bring a personal supply of Imodium (loperamide) for managing symptoms, and ciprofloxacin if your doctor will prescribe it for emergency use. But prevention — treating your water, washing your hands before meals, avoiding raw salads — is worth more than any medicine.

For more health advice, see our altitude sickness prevention guide. And WhatsApp us if you have questions about water treatment or health preparation for your trek.