Osmo Rainstick Water Filter

  • $14.95
    Unit price per 


The Rainstick is a simple membrane envelope with 30 g of our nutrient blend osmotic driver inside. It’s designed for fresh or brackish water sources. Since it comes pre-filled, this single-use filter is simple to use – just drop it in the water source and wait while it hydrates. When it’s done, it provides 355 ml of a clean, refreshing drink. Simply poke with included straw and drink.

5 Flavor Packs per order: Fruit, Orange, Lemon, Mixed Berry and Grape.

  • Bio Rejection: 6-log (99.9999%) bacteriological rejection
  • Metal Rejection: Up to 99A%
  • Hydration Time at 20C:
  • Hydration Time at 30C:
  • Volume When Full: 355 ml individual 

Can I use your filters in ocean water?

Yes, we have 3 filters specifically designed for ocean use: The Seal, the Mariner and the HighSeas. These filters are designed for ocean survival and can be found in many military life rafts around the world.

Is muddy water OK?

Yes! You’ll find that our filters work very well in muddy water.

How many times can I use the filter?

Some of our filters are designed for multiple uses (HighSeas, Ranger, MarinerMulti, Taproot) and some are single use (Rainstick, WaterDrop, Seal, Mariner)

Can I filter radiator fluids?

 No! Never do that, and avoid direct industrial discharge pipes.

What about brackish water?

Even our fresh water filters (Rainstick, WaterDrop, Ranger) will handle brackish water.

How many calories are in the drink?

  • Rainsick: 64 Kcal
  • Waterdrop: 120 Kcal
  • Mariner: 480 Kcal
  • Seal: 450 Kcal
  • HighSeas: 450
  • Kcal per 8 oz

Why do your water filters produce a drink, not water?

All filters require some sort of energy to move water through the filter… whether that’s gravity, hand pumping or an electric pump. The tighter the filter, the more energy required. FTS uses the energy of osmosis to draw water into the filter pouch. That osmotic potential is created by dissolved solids… sugars… inside the pouch. So the resultant clean fluid is a beverage, not water. Osmosis is very powerful! If we were to use hydraulic pressure instead, about 600 psi would be required.


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