Stored water is your first line. But if it runs out, or the tap water becomes unsafe, you need a way to treat what you can find. Six of the 24 national guides we compiled list water purification tablets: France, Latvia, Lithuania, Poland, Slovenia and Romania. All of them treat it as a last resort, not a replacement for a water stock.
The three methods at a glance
| Method | Deals with | Doesn't deal with | Needs |
|---|---|---|---|
| Boiling | Bacteria, viruses and parasites | Chemicals, fuel, salt, cloudiness | A stove, fuel and a pan |
| Purification tablets | Most germs in clear water | Chemicals, salt; work poorly in cloudy water | Waiting time on the packet |
| Portable filter | Bacteria, parasites, sediment | Many don't stop viruses; chemicals | Nothing, but filters wear out |
None of the three makes water safe from chemical contamination. If floodwater, fuel or industrial pollution could be involved, don't drink it, whatever you treat it with.
Boiling
Bringing water to a rolling boil for one minute kills the germs that cause most waterborne illness. It is the most reliable method you have, and the one the authorities usually ask for when they issue a boil-water notice.
The catch is energy. Boiling needs a stove and fuel, and in a power cut that fuel is also what you cook with. Thirteen guides list a camping stove; if yours is one of them, factor water into your fuel. Let boiled water cool in a covered pan and store it in a clean container with a lid.
Purification tablets
Tablets are small, light and cheap, and they keep for a long time in a drawer or a grab bag. Drop them in, wait the time printed on the packet, and the water is safe from most germs. They don't remove chemicals or salt.
They work best on clear water. If the water is cloudy, let it settle and pour it through a clean cloth or coffee filter first. Follow the dose and waiting time on the pack exactly; they differ between products.
Portable filters
Pump, squeeze and straw filters push water through a fine membrane. Most remove bacteria, parasites and sediment, which also makes cloudy water clearer. Many do not stop viruses, which are much smaller, so check what the maker claims. Like the other methods, they don't make chemically contaminated water safe.
Filters are popular with hikers, and they suit a grab bag if you might have to leave on foot. At home, with a stove, boiling usually does the job better. A filter and tablets together cover each other's gaps: filter first to clear the water, then use a tablet for viruses.
Which water to treat
Treat the cleanest water you can find, in this order:
- Your own stored water, which needs no treatment if the containers were clean.
- Rainwater collected in clean containers.
- Streams and lakes, only treated, and never downstream of obvious pollution.
Never drink from radiators or central-heating systems, or from toilet cisterns that contain cleaning products.
When the authorities issue a notice
If your water company or local authority issues a boil-water notice, follow it exactly. It may also cover brushing teeth, washing food and making ice. If they say the water must not be used at all, boiling won't help, and you will rely on your stock. Listen to the radio for updates.
What to keep in your kit
- Stored drinking water first: 2 to 3 litres per person per day. See how much water to store.
- A pack of purification tablets, at home and in the grab bag.
- Fuel for boiling, if you have a stove.
- Clean containers with lids for treated water. See emergency water containers.
Our checklist includes purification tablets and sizes your water stock for your household.