Oasis Water Purification Tablets review
By Tom Calder
These are the familiar British Army-issue NaDCC tablets: simple, reliable and inexpensive, treating one litre per tablet in about 30 minutes. For emergency drinking-water backup they are hard to fault, provided you understand what chlorine can and cannot do.
- Best for
- A cheap, compact, long-life backup for disinfecting clear water in a grab bag or camping kit.
- Skip it if
- Your likely water source is cloudy, chemically contaminated or you want better-tasting water
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Researched, not used. We haven't used this product. This review is built from the maker's specifications, owner reports and our own sizing.
What we like
- Very low cost per litre and a long shelf life, so they sit in a kit for years without fuss
- Lightweight and compact NaDCC tablets, well proven and widely used by the military and aid agencies
- Effective against bacteria, viruses and many protozoa in clear water when used correctly
Worth knowing
- Leaves a mild chlorine taste and does not remove chemicals, heavy metals or sediment
- You must pre-filter cloudy water and wait the full 30 minutes, so they are slower and less convenient than a pump filter
Out of stock when we checked: our alternatives
Closest in size first, then by our score. None of them was showing out of stock when we last checked.
Best for A compact chemical backup for a grab bag, treating clear water on the move.
as of 2 Nov 2026, 16:07 GMT · Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product.
Best for A compact, long-shelf-life water backup for a grab bag or travel where you cannot boil or filter.
as of 2 Nov 2026, 16:07 GMT · Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product.ⓘ As an Amazon Associate, PreparedBritain earns from qualifying purchases. We may earn a commission when you buy, or a fee when you request a quote, through our links. When two products are close, commission can decide which one we pick. A clearly better product always wins. Amazon prices come from Amazon's own product data and show the date and time they were retrieved. Prices at other retailers are checked by us, less often. Prices and stock can change at any time, so always check the retailer's price before you buy.
Our review
Oasis tablets are Hydrachem's British-made NaDCC chlorine tablets, the kind issued to the armed forces and aid agencies. One 8.5mg tablet treats a litre of water in 30 minutes, they keep for up to five years, and a strip weighs almost nothing. They disinfect clear water; they do not remove chemicals, metals or mud.
What they are
Hydrachem, a UK maker, lists Oasis tablets as sodium dichloroisocyanurate, or NaDCC, which releases chlorine when it dissolves. Its page gives the 8.5mg tablet as 5 parts per million in one litre, or two litres from a clean source at 2 parts per million, with the water safe to drink in 30 minutes. The range is certified to NSF/ANSI 60 for drinking water treatment chemicals. Larger tablets treat more water, which is why packs differ: check the strength on your pack and dose by its label, as the government's water advice says.
How to use them
Fill a clean container with the clearest water you can find, drop in the whole tablet and let it dissolve, cap the container and wait the full 30 minutes before drinking. Hydrachem's guidance is to dissolve the whole tablet and to filter cloudy water first, through a cloth or a coffee filter, because mud and organic matter use up the chlorine before it reaches the germs. Giving the water a shake and letting it stand uncapped for a while takes the edge off the taste. Our guide to purifying water covers boiling and filtering alongside tablets.
For a family, the arithmetic is simple: the Be Ready checklist's three litres per person per day for three days is 36 litres for four people, which is 36 of the 8.5mg tablets, or a strip of the larger ones. Keep enough for that in the kitchen as well as a strip in each bag.
What they cannot do
Chlorine kills bacteria and viruses and most parasites, but it does not remove chemicals, fuel, pesticides or metals, so flood water that has crossed a road or a farm is not a candidate. Some hardy parasites need longer contact or filtration, which is why a filter and tablets together cover more than either alone. Hydrachem says the tablets keep for up to five years in their sealed strip, with the date printed on the pack. Store them dry and away from heat.
Treated water tastes of the swimming pool for an hour or so; a squeeze of lemon or a squash cordial added after the 30 minutes hides it for children.
How they compare
On our water tablet comparison the Oasis 167mg tablets are the same chemistry sized for 20 litres at a time, which suits a container or a bath rather than a bottle. Aquatabs are the other NaDCC brand, interchangeable in practice. Chlorine dioxide tablets are dearer and slower but better against hardy parasites and kinder on taste.
Our verdict
Buy a strip for every grab bag and the car: the cheapest, lightest way to make clear water safe, from a UK maker, with a five-year life. Skip them as your only water plan at home; stored tap water and a filter cover a lost supply with less fuss, and nothing in a tablet helps with water you can see dirt in.
A researched review, built from the maker's specs, manual and UK listings; facts checked 2 Nov 2026. Sources: Hydrachem: Oasis water purification tablets; Hydrachem: frequently asked questions, including shelf life and cloudy water; UK Government Be Ready: water supply interruptions.
Who shouldn't buy this
Don't rely on these alone if your likely water source is cloudy, chemically contaminated or you want better-tasting water. Pair them with a physical filter, and remember that during a UK boil-water notice simply boiling tap water is free and effective.
Key specs
| Treats per tablet | 1 |
| Active agent | NaDCC (sodium dichloroisocyanurate) |
| Pack size | 50 |
This is a Researched review: we haven't used this product. We check every specification against at least two independent sources, re-check the UK price on a schedule where we can track it automatically, and say plainly who it isn't for. Commissions never change a rating.
Questions
How much water does one Oasis tablet treat?
Hydrachem gives the 8.5mg tablet as one litre at 5 parts per million, or two litres from a clean source. Other strengths treat more, so dose by the label on your pack.
How long do Oasis tablets take to work?
Thirty minutes after the tablet has dissolved, by Hydrachem's instructions. Keep the container capped while you wait.
Do Oasis tablets work on muddy or flood water?
Not on their own. Filter cloudy water through a cloth first, and do not rely on chlorine for water that may contain fuel, chemicals or farm run-off.
How long do Oasis tablets keep?
Up to five years in their sealed strip when stored dry, by Hydrachem. The expiry date is printed on the pack.
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