Hollow fibre squeeze filter, maybe 60 litres through it, mostly from clear mountain streams. Flow has gone from a fast stream to a slow drip. I have backflushed with the syringe several times, hard, and it barely improves. Never let it freeze that I know of. Is it dead, or is there a step beyond backflushing? I have a five day trip in a fortnight.
Also let water settle before you filter when you can. Fill the dirty bag, hang it for fifteen minutes while you eat, then decant off the top. Half the silt drops out on its own.
Before writing it off, do a proper deep clean rather than a field backflush. Fill the syringe with clean water, backflush hard ten to fifteen times, then leave the filter fully submerged in clean water for an hour and backflush again. Cartridges that seem dead often come substantially back after a soak, because the fines lift off rather than being blasted off.
If that does not help, the two likely causes are silt that has bonded in, or a freeze cycle you did not notice. Freezing kills them silently and permanently — no visible damage, and worse, it can fail open. A filter that froze and looks fine is a safety issue rather than a flow annoyance.
With a five day trip in two weeks I would clean it, test it, and buy a spare cartridge regardless. They are cheap relative to the trip.
60 litres is very low for a hollow fibre cartridge, so something in your water was dirtier than it looked. Clear mountain water still carries fine glacial silt and organics you cannot see. Pre-filter everything through a bandana or a coffee filter into the dirty bag — costs nothing and multiplies cartridge life several times over.
A lot of my water this year came from a glacier-fed valley, so that would explain it.
@soloseat_sana · 10mo ago
Carry chemical treatment as the backup rather than a second filter. Weighs almost nothing, does not clog, does not freeze. Slow, and it tastes of nothing good, but it is the difference between a bad evening and walking out.
Reply
Report