This page may contain affiliate links, please check out our disclosure policy here.
Most products have an expiry date and water purification tablets are no exception. Expiration time can vary according to quality and type of purifier.
As a general rule most types of water purification tablet should be used within 4 to 6 years if unopened. The exact expiration date will be marked on the outside of the tablet package. If the package is opened the contents should be used within 1 year, as the chemicals lose their effectiveness.
- Do water purification tablets really work?
- What happens if you drink untreated water?
- What should I do after drinking dirty water?
- How many types of water purification are there?
- Do water purification tablets make water taste bad?
- Can I use expired water purification tablets?
- Are water purification tablets bad for you?
Do water purification tablets really work?
There a several ways water can be polluted, making it unsafe for humans to drink – contamination could include:
- heavy metals
Standard water purification tablets target pathogens as these are the most dangerous in the short term.
Other pollutants tend to be in low concentrations and are not alive. This means they cannot grow and thrive in the human body.
Important Note: Purification chemicals aim to remove pathogens and not other contaminants. They are are not a long term solution.
What is a pathogen simple definition?
Pathogens are living entities such as viruses or bacteria that can multiply and cause disease in the human body.
Video – Guide to water purification tablets
What happens if you drink untreated water?
Pathogens in dirty water can cause diarrhoea, cholera, dysentery, typhoid, gastroenteritis and polio, among others.
These illnesses can be dangerous for children and elderly people, other people with compromised immune systems.
What should I do after drinking dirty water?
First of all, dirty looking water may or may not be dangerous to your health, it all depends what’s in it. Dirt, grit and soil isn’t particuarly dangerous, but it may contain germs and toxic substances.
If you have no symptoms, but you had to drink suspect water, you can chew/swallow charcoal as a quick temporary measure.
Charcoal can absorb a huge amount of pollutants and helps to nullify the effect of poisons in the stomach.
If you have absolutely no symptoms, then you could afford to wait and get a checkup with your regular doctor whenever you. A blood test would show up any pathogens.
If you have any symptoms at all, such as:
- stomach cramps
- stomach ache
- chills and shivering
In these cases, you should get to the hospital emergency room as soon as you’re able.
Table – Water purification expiry dates compared
Potable Aqua Germicidal
Katadyn Micropur MP1
5 years (from date on packet)
Hypoiodous acid and Iodine
Time to Work
30 minutes (up to 4 hours, cold water)
1 tablet for 1-2 litres
1 tablet for 30 litres
1 tablet for 1 litre
2 tablets for 1 litre
1 tablet for 1 litre
4.5 (98 ratings)
4.6 (808 ratings)
4.7 (6144 ratings)
4.5 for 5820 ratings
4.7 for 341 ratings
How many types of water purification are there?
Chlorine dioxide is by far the most common active ingredient found in most water purification tablets.
Like all the others, this type of tablet does very little to remove any bad taste or smell. In fact, chlorine tables give the wate another flavour to add into the mix!
Seperate products are sometimes sold in tablet form to remove tastes and smell. (Think Potable Aqua with PA+Plus tablets.)
Iodine is also used to purify contaminated water but care must be taken with water temperature. In colder water (less than 16 degrees C) it can take twice as long to purify dirty water.
Iodine-based tablets can take longer than chlorine, which is a powerful micro-organism killer.
Aquatabs are a very popular form of tablet. They use a chemical called NaDCC, or Sodium Dichloroisocyanurate.
They do a pretty good job and take a short time relative to their competitors. Katadyn Micropur, for example, can take up to 240 mins compared to 40 mins for Aquatabs and they are affordable.
That said, Katadyn are very efficient and it’s probably worth waiting for purer water. If you’ve ever had dysentry, you’ll know what I mean!
Do water purification tablets make water taste bad?
Different tablets have different taste characteristics depending on the active ingredient:
- Chlorine (bleach) – strong aftertaste and chemical smell
- Chlorine dioxide – slight aftertaste
- Iodine – strong taste like rust
- NaDCC – very slight taste, not disagreeable
How to improve the taste of purified water
Some tablets come with another set of pills that are added after the water has been treated. These ‘taste improver’ tablets contain a chemical such as hypochlorite to absorb the aftertaste.
Effervescent vitamin C tablets can also be added to the water. It’s a pleasant taste and completely disguises any unpleasant taste left by purification tablets.
Can I use expired water purification tablets?
In theory, the active ingredients will just deteriorate or evaporate away becoming less effective. They cannot turn into something dangerous, but will be weaker.
Expired tablets may still work, but not as effectively. It could be tempting to simply double up on the recommended number of tablets – I wouldn’t recommend this.
It isn’t worth taking chances with dirty water. Just replenish your stock of purification tablets when they expire.
Note: Manufacturers always give themselves a safety margin so it would probably be OK to use tablets that are just a few months out of date in an emergency (if you really have to).
In this case, leave the water twice as long before drinking it.
Do aqua tabs expire?
Aquatabs expire, just like any other chemical-based product. In general, they are good for 5 years for the date of manufacture.
Aquatabs are sealed individually in aluminium foil sleeves and the expiry date is printed on each packet. However, this date is only effective if Aquatabs are stored in a cool dry place, and if the wrappings are not punctured.
Do micropur tablets expire?
Katadyn Micropur tablets are silver-based and have a much longer shelf-life than chlorine or iodine-based tablets.
Expiry date is 10 years after the date of manufacture.
Do chlorine Dioxide tablets expire?
As a general rule, all chlorine-based water purification tablets expire after 4 years. I wouldn’t use them much past the expiry date unless in an emergency.
Are water purification tablets bad for you?
Water purification tablest are designed to dissolve in water, killing micro-organisms so that it’s safe for humans to drink.
The very fact that the active ingredient kills living organisms shoud be a red flag – we are living organisms!
In the case of iodine, for example – we all need iodine in minute quantities, but more than 2 grams will kill a human being.
ALL of the chemicals used to purify water will kill you if you swallowed them directly. They are intended to be used strictly as directed by the manufacturers.