Water and Hydration

Picking a water purification system looks simple until you start comparing options. There are three main technologies and each has its place. Gravity filters work with no electricity and no physical effort: you fill the top reservoir, gravity pulls the water through a ceramic or activated-carbon element, and you collect clean water below. They are ideal for use at home during a prolonged supply cut, because you can leave them working while you deal with everything else. Their limitation is throughput, since most process between 1 and 3 litres per hour, which can feel slow for a large family.

Pump filters take manual effort but are far faster and more portable. A good pump filter processes roughly a litre a minute, which makes an enormous difference when you need water for several people or you are on the move. They are the preferred option for evacuation bags and any situation where you cannot stay put waiting. The downside is that you need an accessible water source, and the sustained pumping is more tiring than it sounds, especially under stress or in heat.

Ultraviolet (UV) purifiers are the lightest and fastest option: you stir the lamp in a litre of water and in 60 to 90 seconds it neutralises 99.9% of viruses, bacteria and protozoa. UV is the only one of the three that reliably deals with viruses without chemicals. Its weak point is that it depends on batteries or USB charging, and it struggles with cloudy water because suspended particles create shadows that shield pathogens. If the water is murky, pre-filter it through a cloth or basic filter before applying UV.

My recommendation after years of testing different systems: for the home, a large gravity filter as the primary system and purification tablets as backup. For the evacuation bag, a compact pump filter plus a UV purifier as a complement. Do not marry a single technology. In every prolonged outage I have followed closely, the households that had two distinct methods were the ones that never ran into a drinking-water problem during the critical first days.

The first mistake I see constantly is storing water in thin plastic containers left in the sun or next to a heat source. The polyethylene of cheap supermarket jugs is not designed for long-term storage. With heat it releases compounds that spoil the taste and, in the worst case, can be harmful. If you are storing water for months, use food-grade high-density polyethylene (HDPE) containers and keep them somewhere cool and dark. An interior cupboard, a storage room or under the bed all work well.

Another frequent error is calculating only drinking water and forgetting that you also need water for cooking, basic hygiene and, if you have pets, for them too. The 3-litres-per-person-per-day rule that civil protection agencies publish is an absolute survival minimum. In practice, with cooking and minimal hygiene, you need between 4 and 5 litres per person per day. I learned that the hard way during a week without supply: by the third day I was already rationing cooking water because I had only planned for drinking.

The third mistake is failing to rotate stored water. Commercial bottled water has a best-before date, usually one to two years out. It does not turn toxic past that date, but the taste degrades and the plastic can break down. The fix is to build rotation into your routine: every six months, use the stored water for plants or cleaning and refill with fresh. That way you always have a current reserve and waste nothing.

A fourth mistake few people mention: blindly trusting a single purification method you have never actually tried. I have seen people buy a filter, leave it sealed in the bag, and assume it will work when they need it. Test it at least once. Learn how it assembles, how long it takes to filter a litre, and check that the output tastes clean. That ten-minute rehearsal can spare you a serious problem when you genuinely depend on it.

Maintaining the water system matters as much as owning it. A filter with an expired cartridge or a jerry can with algae in the bottom is worse than nothing, because it gives you a false sense of security. Correct maintenance has three legs: static storage, filters, and purification tablets.

For static storage, the keys are darkness, stable temperature and cleanliness. Wash containers with a diluted food-safe bleach solution (about 8 drops per litre, leave 30 minutes, rinse well) before the first fill. Once full, mark them with the fill date and plan rotation every 6 months. If you use transparent or translucent containers, cover them with dark cloth to stop algae growth from light exposure.

Ceramic and activated-carbon filters have a service life measured in litres processed, not in time. A Katadyn BeFree lasts around 1,000 litres; a ceramic gravity cartridge can reach 20,000 litres. Track the litres you filter or, if you use it rarely, replace it every two years as a precaution. Activated-carbon filters lose effectiveness over time even unused, because the carbon absorbs compounds from the air, so keep them sealed in their original packaging until the moment of use.

Purification tablets carry a manufacturer expiry, generally three to five years sealed. Once opened, their effectiveness drops quickly through air exposure. Buy small packs of 50 to 100 tablets and do not open the blister until you need them. In your evacuation bag always carry an unopened blister and check the expiry date every time you review the kit, which should be at least twice a year.