What chemical pollutants and why?
h2osurvivalstraw
Last time someone mentioned h2osurvivalstraw I did some light searching, found its rebranded chinese product, with photoshopped ads

See for yourself Diercon PS01-01

They claim various certifications but none are listed for that model
http://wqa.org/Find-Products#/keyword/Diercon
carbon ceramic for PB01 which is dierconpb01-01-22 ceramic candle with charcoal inside

On the PS01-01 they also claim its PB01 model ... sloppy info

The other sneaky claims
But its only reduces
EPA chlorine minimum for virus reduction/inactivation is 99.99% or 4-logr, but its 6-logr / 99.9999% for bacteria

Sure, there is some chinese certification listed, but its in chinese...
update: right, water-test-certification english version , basically its just bacteria reduction test again, 99.99% ...

update: great criticism of product here , the rebranding label covers the warning (dont use on nasty water), and backflushing is impossible
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seychelle
seychelle is even more meh, the two under $20 deals are activated carbon taste filters (1-50302-C - ADVANCED Drinking Straw and regular 1-50102-C )
... 99% reduction of bacteria that's folded cotton cloth level of filtration

I guesstimate (rounding up) about $3 bucks worth of store bought activated carbon in a $1 plastic bottle


Then the $44.95 version , 1-50602-C - RAD/ADV Drinking Straw / Radiological Advanced filter, has ion exchange balls to reduce ions

I don't know what ion exchange resin beads sell for ... not really worried about heavy metals in the tapwater

They all have a capacity of 25 gallons

update: brita pitcher filter lasts 40 gallons or two months, one filter can be had for $5 to $8 (3 pack versus 1 pack)
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renovo

renovo looks to be backflushable, the only deal I'd consider investigating because of form factor -- but if you look at the info they provide its also very much meh , they only claim
removes (99.99%) Bacteria, Protozoa, Chemicals, and even some Viruses.

Renovo_Trio_Test_Results.pdf lists number but not comparable numbers, no log reductions, no percentags -- consumers don't like math, when manufacturers make consumers do math, they're trying to pull a fast one

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conclusion
All filter salesmen everywhere claim Meets or exceeds EPA standards ... but they usually don't say which standard


So, ignoring that I'm not a fan of the form factor, I'd pass on all three