Water filter jug vs emergency water filter: which one helps in an emergency?

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A filter jug is for taste. The Drinking Water Inspectorate says the most common reason to buy a filter is to remove tastes and smells from tap water, which is already safe to drink. It does not say a jug makes unsafe water safe, so under a boil water notice you boil the water as told. For an emergency, bottled water comes first; for doubtful water, official advice is to filter it until clear, then boil it or use purification tablets.

What does a water filter jug actually do?

The Drinking Water Inspectorate (DWI) has a page on home filters. Writing about England and Wales, it says:

• Tap water is already safe. Public supplies are tested regularly, and the DWI says there is no need to add treatment at home to protect your health.
• Taste and smell are the main reason people buy a filter. Taste varies between regions because of water hardness and the small amount of chlorine kept in the water to keep it safe.
• Choose activated carbon if taste is your reason, and change the cartridge when the maker says. If you don't, the DWI says the filter stops working and may release chemicals or bacteria back into the water.
• A cheaper option is a clean, covered glass jug of tap water kept in the fridge.

So a jug filter is a comfort item for safe mains water. Nothing on the DWI page presents it as a way to make unsafe water drinkable.

Can a filter jug make unsafe water safe?

Don't rely on one for that. The DWI's advice on home filters is written for tap water that is already safe. Its separate guidance on point of use treatment (devices fitted at a single tap on private supplies) says any device used to make water safe must be suitable for the risk it is meant to control. A countertop jug bought for taste was not chosen for that job.

If the label on any filter does not say what germs it removes, assume it doesn't.

What should I do under a boil water notice?

Follow the notice, not your filter. The DWI's boil water notice page says a notice means tap water might contain bacteria, viruses or parasites. It says:

• Boil water before you drink it, brush your teeth, make ice cubes, prepare food, clean feeding equipment or give it to pets.
• Bring it to a rolling boil, take it off the heat and let it cool naturally.
• Store it in a clean container in the fridge and throw it away if not used within 24 hours.
• Take care: boiling water can scald.
• You can still shower and bathe, but don't let the water get into your mouth.

Very occasionally you may be told not to use tap water at all. Then the DWI says drink bottled water or the alternative supply from your water company. Our boil water notice guide has the full list.

Jug, portable filter, boiling or tablets: which does what?

What can emergency filters miss?

The US CDC's emergency water page gives the clearest plain summary we found:

• Viruses. Portable filters will not remove viruses. To deal with them, the CDC suggests adding a chemical disinfectant after filtering.
• Some parasites with tablets alone. Chemical disinfectants kill viruses and bacteria but may not kill parasites such as Cryptosporidium and Giardia as well as boiling does.
• Fuel, chemicals and radioactive material. The CDC says you cannot make water with these in it safe by boiling or disinfecting it. Don't drink it.

That is why the official approach uses steps together, rather than trusting one gadget.

What is the official UK method if the taps stop?

Start with bottled water. GOV.UK Be Ready recommends 3 litres of drinking water per person per day for 3 days, and calls bottled water the safest way to prepare. If you have no space for bottles, it says boiling or adding purification tablets to other water sources can make it safer, and that most such water will need filtering first.

The UK Chief Medical Officers' water scripts for a national power cut set out the order for doubtful water:

1. Collect it in a clean container that has never held fuel or paint.
2. If there is an oily film on top, don't drink it.
3. Pour it through a coffee filter, pillowcase or sheet until it runs clear.
4. Then disinfect it: boil it, or use in-date purification tablets.

They treat river water as a last resort. Be Ready also says rainwater from a water butt is for flushing and plants, not drinking. Our make water safe to drink post covers this step by step, including their last-resort method.

So which should I buy?

For most UK homes, in this order:

• Bottled water first. 3 litres per person per day for 3 days (Be Ready). See how much water to store in a small flat.
• A way to boil water, because the DWI calls heating water one of the best ways to kill germs, and the CDC calls boiling the best way.
• In-date purification tablets for when you can't boil. Our purification tablets vs iodine tablets post explains which kind.
• A portable filter, if you want one, for clearing cloudy water before you boil or disinfect it. Check what the label says it removes, and keep spare cartridges.
• A filter jug only if you dislike the taste of your tap water. It is not an emergency item.

If you want to store more water than a few packs of bottles, see our water storage advice in the posts linked above before you buy containers.

Before you buy any home filter

The DWI suggests asking your water company for a free copy of the water quality report for your home first. It shows the legal standards and the levels found in your water. It also warns: don't buy from door-to-door sellers who offer to "test" your water to show it is contaminated, and report them to trading standards. If you have no water at all, check your company's live updates with our no water in my area tool.

Related guides

• Boil water notice: what it means and what to do
• Emergency water at home: how much to store and how
• No water supply: what to do, and what you're entitled to

Free tools

• No water in my area: your water company's live page
• Emergency supplies calculator (how much water to keep)

We're an independent UK site, not the government. We check guides against official sources and link to them. In an emergency call 999.

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