I bought this product, got one nalgene bottle out of it, before it completely clogged.  I tried cleaning it with the sponge it comes included with, and that helped, temporarily.  The problem seems to be that the valve that is supposed to keep the water from going back out the intake tube, was defective.  You SQUEEEEEEEEEEEEEEEZE so hard (the pump is VERY hard to push)only to have a drop come out the bottom, and all the rest go back out into the stream.

Another person with the exact same, brand new filter, offered to let me use his.  The same thing happened!!!  Luckily, there was someone along with a Pur filter and we all just had to use hers.  This would have left us for 3 days in the wilderness with no water if we had just relied on this filter.  UNACCEPTABLE for a product like this!!!

I returned it, and will go get a Pur filter.  The woman who let us use her Pur filter said everyone she knows who uses this filter has problems with it.  Strange, because all other MSR products are so good.  I wonder if there was a manufacturing defect with this latest batch, since both of us had bought it new, and had the same problem.  Who knows.  Anyway, i would give this zero stars if it was possible.
I bought this product, got one nalgene bottle out of it, before it completely clogged. I tried cleaning it with the sponge it comes included with, and that helped, temporarily. The problem seems to be that the valve that is supposed to keep the water from going back out the intake tube, was defective. You SQUEEEEEEEEEEEEEEEZE so hard (the pump is VERY hard to push)only to have a drop come out the bottom, and all the rest go back out into the stream. Another person with the exact same, brand new filter, offered to let me use his. The same thing happened!!! Luckily, there was someone along with a Pur filter and we all just had to use hers. This would have left us for 3 days in the wilderness with no water if we had just relied on this filter. UNACCEPTABLE for a product like this!!! I returned it, and will go get a Pur filter. The woman who let us use her Pur filter said everyone she knows who uses this filter has problems with it. Strange, because all other MSR products are so good. I wonder if there was a manufacturing defect with this latest batch, since both of us had bought it new, and had the same problem. Who knows. Anyway, i would give this zero stars if it was possible.