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Miniwell water filter kit

May 12, 2021 — BarryK

I am continuing to iterate through the gear that will go into the Daylight Lumbar Pack, aiming to reduce the total weight from 4.5kg to 3.5kg. Earlier this year, I reconsidered the base load, without shelter and sleeping gear:

The water filter kit had a Sawyer Mini, a flat bottle, tube and syringe. I reckoned that the syringe could be left home, so the weight was 82g:


There are two serious problems with that kit...

Firstly, I have discussed in previous blogs about the bottle wanting to stay flat and being a pain to fill from a pond surface.

I found a foldable TPU bottle that has a natural tendency to stay open, and can be filled from a pond surface in a few seconds. So I am now using this one instead of the Sawyer bottle, and it even weighs less -- I am using a lid from a soft drink bottle and total weight of bottle is now 21g. This is what I purchased, 500ml dark green (so as to distinguish from my clean-water TPU bottles, that are all light blue):

Secondly, The Sawyer Mini is very restricted in how it can be used, by not having threads on both ends. So, it has been retired, and I am now using a Miniwell filter:

This has a 28mm thread on both ends, opening up lots of extra possible configurations. You could, for example, squeeze directly from one TPU bottle into another. As the clean-water bottle can be rolled up and most air expelled, there is no problem with screwing it onto the outlet of the Miniwell filter and filling it with filtered water.

Here is a photo of my new kit:


For minimalist hiking, only the filter and bottle are required. Weights:

Miniwell filter
TPU bottle

The "dirty" water bottle also has another use, with the bidet. If you haven't been following my blog posts, here is one about a portable bidet:

However, those other parts in the above photo are very useful. One problem with filtering water is that it takes time. If you arrive at a campsite, or anywhere where there is a water supply, it could take some time to fill up the filtered-water bottles.

Of course, a way around that is to just put the "dirty" water into all the bottles, and always drink through the filter. But for now, I won't go that way.

What is really nice is to have a plastic bag filled with water and let gravity do the job of filtering. That way, you can be doing other things, setting up tent or whatever, while the filtering happens. Here is a photo showing those other parts in action:


...that little white thing is a hose clamp. Bottom-left, using a plastic single-use shopping bag, they weigh virtually nothing.

You see the guy drinking from it, but a rolled-up TPU bottle could be screwed-on and left to fill, while you are off doing other things.

Here are the weights:

Silicone tube
Hose clamp

The grand total then becomes 105g. I do not want to be going up in weight, though these extra items are very useful.

The silcone tube is very heavy. Measuring with my measuring tape, ID (inside diameter) is 5.5mm, and OD is 8.5mm. Quite thick walls. I could replace with thinner tube, and reckon knock the weight right down, to under 10g.

That clamp is not really needed, only have to crimp the tube to stop water flow, could do that with an elastic band. So could end up with a total weight around 84g, almost same as before. But much more versatile.

Note, that tube is required for gravity filtering, as there has to be a certain head of water to get enough pressure.

Oh, one more point about the Miniwell kit: a syringe is not required for back-flushing. Any old flexible plastic bottle with 28mm thread will do. Fill it with clean water, even tap water when you reach civilization, screw onto the filter outlet-end, and press very firmly. Another advantage with having threads both ends!

EDIT 2021-05-24:
I have purchased silicone tube with 5mm ID (inside diameter) and 6mm OD (outside diameter), so the wall thickness is only 0.5mm. Very thin, so kinks easily, but it works. Although only 5mm ID, it still fits onto the Miniwell filter and to the gravity-bag adapter. The silicone tube supplied with the Miniwell kit is 60.5cm long. I purchased 100cm of this thin tube, and will use the entire length for gravity-feed, as the more water-head the better.

The new tube, 1 metre, weighs just 13g. Bought from here:  

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