How to make your drinking water safe at home
A plain-language guide to treating drinking water at home in Nepal — boiling, filtering, chlorination, solar disinfection and combining methods — so you and your family avoid diarrhoea, typhoid and other waterborne illness.
In much of Nepal, the water that reaches your tap, well, jar or tanker is not automatically safe to drink. Pipes leak, tanks sit uncovered, monsoon floods wash contamination into sources, and load-shedding or supply cuts mean water often stands for days. Unsafe water is one of the most common causes of diarrhoea, typhoid, jaundice (hepatitis A and E) and worm infections, especially in young children.
The good news is that you do not need expensive equipment to make water safe. A few simple, proven methods — done correctly and consistently — remove or kill the germs that cause illness. This guide walks through each method, when to use it, and how to do it properly, with options for every budget.
Treat treating-water as a daily habit, like locking your door. Even when water looks clear, it can carry germs you cannot see. The aim is simple: every drop your family drinks or uses for cooking, brushing teeth or making baby formula should be treated.
First, judge how risky your water is
Different sources carry different risks. Knowing your source helps you choose the right method and decide how careful to be.
If your water is cloudy or muddy (common during the monsoon or from rivers, shallow wells and some tankers), you must clear it first — most treatment methods work poorly on dirty water. Let it settle, or strain it through a clean cotton cloth folded several times, before treating.
- Higher risk: river, stream, shallow/open well (kuwa), pond, untreated tanker water, and any source after heavy rain or flooding.
- Medium risk: piped municipal supply (it can pick up contamination from leaks and storage), deep tube wells.
- Lower but not zero risk: properly sealed jar/bottled water from a trusted brand — still store and handle it carefully.
- Always assume water is unsafe to drink unless you have treated it yourself or know for certain it was treated.
Method 1 — Boiling (the most reliable)
Boiling is the single most dependable way to kill bacteria, viruses and parasites. If you have a gas, induction or biogas stove and can afford the fuel, boiling is the gold standard, especially for babies, sick people and during an outbreak.
The mistake people make is taking water off the heat too soon. You need a true rolling boil — big bubbles breaking the surface continuously — not just steam or small bubbles.
- If the water is cloudy, filter it through a clean cloth first.
- Heat the water until it reaches a full rolling boil.
- Keep it at a rolling boil for at least 1 minute (let it boil 3 minutes if you live in the high hills or mountains, where water boils at a lower temperature).
- Let it cool with the lid on. Do not dip cups or hands into it.
- Store the boiled water in a clean, covered container and use it within 1–2 days.
Method 2 — Chlorination (cheap and scales well)
Adding a tiny, measured amount of chlorine kills most germs and keeps protecting the water for a day or two — useful when fuel is short, during emergencies, or for treating a whole jar or drum at once. In Nepal you can find liquid chlorine solution (such as Piyush/WaterGuard-type products sold at pharmacies and through health programmes) and chlorine tablets (like Aquatabs).
Always follow the exact dose printed on the bottle or tablet packet, because product strengths differ. Chlorine works best on clear water, so filter cloudy water first. After dosing, stir, then wait the recommended time (usually about 30 minutes) before drinking. A faint chlorine smell is normal and tells you it worked; if there is no smell at all, the dose may have been too small or the water too dirty.
- Best for: treating larger amounts, emergencies, floods, and when boiling is not practical.
- Not ideal alone for very cloudy or chemically contaminated water — clear it first.
- Keep chlorine products tightly capped, away from children, and note that liquid solution loses strength over months — check the expiry.
Method 3 — Filtering
Household filters range from simple ceramic candle filters and gravity 'bio-sand'/membrane filters to branded units. A good filter removes dirt, many bacteria and parasites, and improves taste — handy for everyday drinking water. Quality varies hugely, so choose a filter that clearly states what it removes.
Remember two limits: most basic filters do not reliably remove viruses, and a dirty or cracked filter can make water worse, not better. The safest approach in higher-risk situations is to filter and then disinfect (boil, chlorinate, or use SODIS) — see the combined method below.
- Clean and replace filter candles/cartridges exactly as the maker says — a clogged or slimy filter breeds germs.
- Keep the clean-water side and the dirty-water side separate; never let hands or dirty cups touch the treated water.
- Filters that say they remove bacteria and protozoa are good; for full safety against viruses, disinfect after filtering.
Method 4 — Solar disinfection (SODIS), the no-cost option
SODIS uses free sunlight to kill germs and is ideal when you have no fuel, chlorine or filter. It works because the sun's UV rays and heat damage the germs in the water.
It only works on clear water in clear PET plastic bottles (the thin, see-through kind), and it needs strong sun — so it is reliable on bright Terai and hill days but slow or unreliable in cloudy monsoon weather. Treat SODIS as a useful backup rather than your only method during the rains.
- Use clean, clear PET plastic bottles (avoid scratched, coloured or thick bottles).
- Filter cloudy water through cloth first — SODIS fails on dirty water.
- Fill bottles about three-quarters, shake for 20 seconds to add oxygen, then fill to the top and cap.
- Lay the bottles on their side in full sun (a tin roof works well) for at least 6 hours on a bright day, or 2 full days if it is cloudy.
- Drink straight from the treated bottle to avoid recontamination.
Combine methods for the safest result
No single low-cost method is perfect for every situation. The strongest, widely recommended approach is two steps: first make the water clear (settle or filter), then disinfect it (boil, chlorinate or SODIS).
For example, during a flood or outbreak: strain muddy water through cloth, run it through a filter if you have one, then either boil it or add the correct dose of chlorine. For everyday tap water that already looks clear, boiling or correct chlorination on its own is usually enough. Whatever you choose, store the treated water safely — handling it badly can undo all your work, which the storage guide covers.
Key takeaways
- ✓Assume all untreated water is unsafe to drink, even when it looks clear.
- ✓Boiling to a rolling boil for at least 1 minute (3 minutes in the high mountains) is the most reliable method.
- ✓Chlorine drops/tablets are cheap and protect water for a day or two — follow the exact dose and let it sit ~30 minutes.
- ✓Always clear cloudy water (settle or strain through cloth) before treating it.
- ✓Filters improve taste and remove many germs but often miss viruses — disinfect after filtering for full safety.
- ✓The safest routine is two steps: make the water clear, then disinfect it; then store it covered.
How to Make Drinking Water Safe at Home (Boiling, Filtering & SODIS) — FAQ
Is my municipal tap water in Kathmandu safe to drink directly?+
Treat it as unsafe to drink without treatment. Even where supply is chlorinated at source, leaking pipes, intermittent supply and household storage can let germs back in. Boil, filter-and-disinfect, or chlorinate before drinking, and never drink straight from a storage tank or jar without treating.
Does boiling remove chemicals like arsenic or pesticides?+
No. Boiling, chlorine and SODIS kill germs but do not remove most chemicals; in fact boiling can concentrate some. Arsenic is a known problem in parts of the Terai — if that is a concern in your area, you need a specific arsenic-removal filter or an alternative source, not boiling. Ask your local health post about arsenic testing.
How long does treated water stay safe?+
Use boiled or filtered water within 1–2 days and keep it covered. Chlorinated water stays protected a little longer because chlorine keeps working, but still use it within 2 days and store it cleanly. Every time you dip a hand or dirty cup in, you risk recontaminating it.
Can I just buy jar water instead?+
Sealed jar or bottled water from a trusted, licensed brand is generally a reasonable option, but quality varies and refill jars can be contaminated during refilling or storage. If you rely on jar water, buy from a reputable supplier, check the seal, and store and pour it hygienically.
What is the cheapest way to make water safe?+
SODIS (solar disinfection) costs nothing but the bottles and needs strong sun. Chlorine drops/tablets are very cheap per litre and work in any weather. Boiling is reliable but uses fuel. Pick what matches your budget, fuel access and the weather.
Sources & data note
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