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Water filters · two straws

Purewell straw filter, 0.01 micron stated, 1500 litre cartridge vs Waterdrop straw filter with gravity bag, 0.1 micron stated, 5300 litre cartridge

Two straw filters, two stated pore sizes — what does each maker actually put in writing?

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Both of these are straws, both are sold to be drawn at the source, and both state a pore size and a cartridge life. Neither states a flow rate, and neither does any of the other seven filters in this hub: nine listings, nine blanks, in the column that would tell you how long a litre takes. Nothing on this page says what either device makes water fit for — that is a question for the maker’s instructions and for the authority responsible for the water in front of you.

Purewell outdoor straw water filter with a carabiner clip

Purewell straw filter, 0.01 micron stated, 1500 litre cartridge

Wins 2 of 8

Check price

≈ 15 €

Waterdrop light blue outdoor filter straw with a gravity water bag

Waterdrop straw filter with gravity bag, 0.1 micron stated, 5300 litre cartridge

Wins 3 of 8

Check price

≈ £28 / 28 €

Line by line

Compared on straw filter, 0.01 micron stated, 1500 litre cartridge straw filter with gravity bag, 0.1 micron stated, 5300 litre cartridge
Micron rating 0.01 micron — stated twice, as 0.01 μm in the title and as a filtration accuracy in the bullets 0.1 micron — stated as a 0.1 µm ultrafiltration membrane
Filter element type Four stages, all named — a hollow-fibre ultrafiltration membrane, PP cotton, coconut-shell activated carbon and an adsorption ball Coconut-shell activated carbon with a 0.1 micron ultrafiltration membrane — stated
Stated flow rate Not published Not published
Cartridge life 1500 litres — stated Up to 5300 litres — stated
Weight Not published Not published
Format Straw with a carabiner — the maker states it can be drawn at the source or fitted into a water bottle Straw with a gravity water bag — the maker states both ends come apart and that it works with bags or bottles
Stated way to restore flow Not published Backflush without a separate syringe — stated
Bottle thread compatibility Not published — the maker states the filter is inserted into a water bottle and never gives a thread size Not published — the maker states it can be combined with water bottles and gives no thread size

Each tick belongs to its own line and nothing more. The row of ticks is not a score: the two verdicts underneath settle the page, because these two answer different questions on the trail.

Which one, for whom

Buy the Purewell straw filter, 0.01 micron stated, 1500 litre cartridge

The Purewell states the finer pore size of the two, 0.01 micron against 0.1, and it is the only filter in this hub that names all four stages of its element rather than one or two. Its stated cartridge life is the shorter, 1500 litres, and what any of that means for a given water is set out in the maker’s instructions, not here.

Buy the Waterdrop straw filter with gravity bag, 0.1 micron stated, 5300 litre cartridge

The Waterdrop states more than three times the cartridge life, up to 5300 litres, and it arrives with a gravity bag and a stated way of restoring flow without carrying a syringe — the only listing on this shelf to publish that. Its stated pore size is the coarser of the two, and the two figures are the maker’s, not a result.

What people ask before buying

Does a smaller micron figure mean cleaner water?

This page will not say so, because a stated pore size is a manufacturing specification and not an outcome. What each filter is for, what it is not for, and what has to be done before or after it are set out in the instructions supplied with it, and the water you are standing in front of is the business of the local authority responsible for it.

Why is the flow rate column blank on both?

Because no maker on this shelf publishes one — nine filters, nine blanks. Purewell says nothing at all; Waterdrop says nothing either. The nearest thing to it here is Waterdrop’s stated backflush, which addresses flow that has already dropped rather than the flow you start with.

The full reviews

Prices in these summaries were read on the dates each review gives. The live figure sits beside every product.