How Effective are Backflushing and Storage Practices for Squeeze Filters

[David D]

Currently have 5 filters in house, partly for different use cases

– Quickdraw (+backup) for most trips

– Gravityworks (+backup filter) for 3+ people trips

– Trailshot (a carpal tunnel syndrome generator), great for sneaking water out of small clean-water pockets in lakes heavy with decomposed veg late season

Use them all, but ya, a bit of a PITA

[tkkn c]

I use an aquarium air pump to dry out my filters and hydration bladders.

[Arthur]

My filter life got much better when I started using distilled water for final rinse.  In AZ, the typical tap water has about 450ppm dissolved solids.  Springs similar.  For reference, many CO streams on the front range are about 40-50ppm.  Distilled water from the grocery store has about 5ppm.

[Todd T]

My filter life got much better when I started using distilled water for final rinse. … Distilled water from the grocery store has about 5ppm.

Ditto.  Just be sure to buy actual distilled water, not something labeled “purified water.”

[David D]

Cascade Designs provided a helpful response.  Probably minerals, with vinegar solution soak to clear.

In future I’ll be disinfecting with bleach solution followed by distilled back flush, followed by accelerated drying like always

[Jerry Adams]

from some other thread, CLR is another product to clear a filter.  It has stuff in addition to acid.  It’s designed to dissolve mineral buildup.

[David D]

Jerry, I’d avoid that stuff for a filter.  Nasty side effects if you then disinfect with bleach:  “Calcium, Lime and Rust Remover should never come into contact with chlorine (or any other household chemical). It can create a poisonous gas and is not safe. “

[Jerry Adams]

That makes sense.

You’d definitely want to rinse it out well afterwards.  Maybe this would be a good treatment for a badly calcified filter which could happen with bleach and hard water.

[David D]

Turns out that vinegar and bleach mixed also create chlorine gas.

I asked Cascade Designs and they advised to rinse with 5-6L of water after the vinegar treatment, before using a bleach solution to store.

So: vinegar soak to demineralize, followed by 5-6L of distilled to rinse, then bleach treatment, followed by distilled rinse to avoid bleach deposits that can block the filter and finally fully dry (fan etc) before storing.

Its crazy that this sort of information isn’t just readily available.

[Roger Caffin]

Getting a bit complex.
Or just use a Steripen UV wand?

Cheers

[David D]

Yup, complex, but puzzling that this process end to end is a mystery requiring self-discovery.

Water out here is often turbid after July.  And my plans are to go deeper and deeper into bushwhacking areas most others would eschew.  Steripen is too risky

[Roger Caffin]

I am curious: why is a Steripen too risky?
Given that UV treatment is used by many city water boards and by the US military.

Granted, turbid water can be a problem for UV, but surely a walker would try to filter the mud out first? One or two coffee filters would work great. One would not want to drink mud after ll.

Cheers

[David D]

It’s the turbidity.   I’d consider a Steripen if pre-filtering didn’t add so much delay.  I often need to filter 5-6L in a day, solo so the time hit isn’t minor.

It’s much quicker and simpler to use a squeeze filter and back flush often but still have to pre-filter late season when lake weeds are dying off.

I’ve tried coffee filters & bandanas but the best pre filter I’ve found (quickest, effective, durable, fast drying) is a baby wipe over a wide mouth Nalgene.  It’s still more hassle, weight and wait than I like to deal with when covering a lot of ground.

Letting suspended goodies settle at the bottom of a 6L Gravity Works is a good compromise for mellow group trips but those happen only once or twice a year

[Roger Caffin]

Consider me ignorant (or just a long way past babies).
Is a baby wipe wet or dry?
Either way, what chemicals are on a baby wipe?

Cheers

[David D]

Initially dry, 2g each

Chemical breakdown is shown here, pretty safe but the prefiltered water is also being run through a Quickdraw filter afterwards

[Roger Caffin]

Hi David

Thank you for that. That web sites lists the following ingredients in one line of wipes:

Polypropylene, wood pulp (cloth material)
Water
Caprylyl Glycol
Sodium Benzoate
Coco-Betaine
Polysorbate 20
Butoxy PEG-4 PG-Amodimethicone
Malic Acid
Sodium Citrate
Tocopheryl Acetate
Glycerin
Fragrance
Aloe Barbadensis Leaf Extract
Cucumis Sativus (Cucumber) Fruit Extract
Calendula Officinalis Flower Extract
Camellia Sinensis Leaf Extract

I am sure some of that is ‘mostly harmless ‘, but why would a mother want to put all of that on her baby? I am boggled!

Not sure I want to drink water which has been through all that either. To be sure, I may be paranoid, but why take the risk? After all, we have been assured in the past most earnestly that XYZ chemicals are perfectly safe – things like asbestos and thalidomide for instance. And the lead in petrol.
Yeah, paranoid.

Cheers

[David D]

Hi Roger, you’re welcome. I think this is pretty safe for a few reasons.

First, the way I prefilter is to wrap the material around the mouth of the dirty bottle, submerge it all and then burp the bottle under water to fill it.  It fills pretty quickly.  The water passes through less than a square inch of material with very little contact area and under low pressure.

Secondly, the article grades the toxicity of each ingredient and by far the most “toxic” is polypropylene, “the safest of all plastics”.  We drink from plastic on trail

Third, the quickdraw will filter chemicals which a steripen can’t do.  In some waters with public use, farms or cottages there can be fertilizer run off, gas, oil etc. in the water

So water run through one square inch of diaper wipe with no known toxicity under low pressure & then filtered through a quickdraw is probably lower risk than filtered through a coffee filter which only removes chunks and then sterlizied with a steripen which can’t remove chemicals and in turbid water will not sterilize to the # of 9’s the hollow tube filter will

[tkkn c]

What is the advantage of using a baby wipe over using a bandana to pre-filter?

[David D]

Baby wipe absorbs a lot less water than a bandana and dry much more quickly.  You can tear off a small piece and get a lot of use from one.  They have dual use later for really dirty stuff clean up.  They weigh 2g each when dry.

Baby wipes and a Buff cover more needs and better than a bandana in my experience.  The wipes are better for filtering and cleaning and a the buff for wearing, with no weight penalty.  And cleaning pots, filtering or cleaning dirt off your tent doesn’t mean you have to choose between wearing a wet bandana or nothing

The wipe doesn’t last for ever but I can get a week out of 3 (6g) and still have the Buff for back up.  Exhausted wipes go in my garbage bag to carry out but they dry fast so there’s little dead weight to carry.

They work for me and I personally find this method much more pleasant and functional than a bandana

[David D]

Another option for pre-filter.  This one by CAMCO meant for water filters so the mesh is fine pitched.   2g.  Fits Quickdraw+Smart bottle.  Will be giving it a spin all next week

[Jeff McWilliams]

David – The Platypus QuickDraw does NOT filter chemicals and toxins.

Says so right on their webpage:  https://www.platy.com/filtration/quickdraw-filter/quickdraw-filter.html

It’s a hollow fiber filter similar to a Sawyer Squeeze.

[David D]

Jeff, thanks for the catch.  I try to be careful to have facts correct especially when discussing safety items, so sorry to have missed that, it’s important.

To filter chemicals in a hollow tube filter, one needs to move up at least to the 6 oz Versaflow with activated carbon:

https://hydroblu.com/versaflow-with-activated-carbon-filter/

“Activated carbon adsorbs chemicals and heavy metals… removing pollution, poisonous, and heavy metal iron from the water…will remove unhealthy organic compounds such as chlorine, pesticides, herbicides, gasoline, and diesel”

The “N” 9’s benefit of hollow tube still remains over a steripen in turbid water though

 

[Roger Caffin]

“Activated carbon adsorbs chemicals and heavy metals… removing pollution, poisonous, and heavy metal iron from the water…will remove unhealthy organic compounds such as chlorine, pesticides, herbicides, gasoline, and diesel”

I think that should read “Activated carbon adsorbs a percentage of the chemicals and heavy metals… “., and so on.
Nothing absorbs 100%. So there can still be a risk, especially with small hand-held units.

Actually, I don’t think any of our portable field units, be they filters, chemicals or UV, can completely remove dissolved chemicals. Industrial and agricultural chemicals are generally bad news. Find another water source.

Cheers

[David D]

I’m thinking when you have to work with the water sources you’ve been dealt (parts of the CDT for example with it’s sketchy green water sources), this hydroblu with activated carbon looks like a big step up over the usual sawyer.  I’m surprised we don’t hear more about it

[William Chilton]

this hydroblu with activated carbon looks like a big step up over the usual sawyer.  I’m surprised we don’t hear more about it

I have no personal experience with it, but the Hydroblu carbon filter is reported to be very slow, so much so that it doesn’t really work as a squeeze filter and it’s better to hang it.

[Author]

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