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Review of Sawyer Just Drink Inline Water Filter (SP121)

I recently purchased the Sawyer SP121 Just Drink Inline Water Filter as a really long term water treatment option. While I have Berkey filters and plenty of chlorine bleach, I wanted something that could seemingly last forever if treated well and not break the bank at that. This particular Sawyer water filter seemed to fit the bill. You can learn more about Sawyer’s water filter technology here.


To get started, here are some specs about the filter from Amazon:

  • Biological Filtration: Sawyer Water Filters offer the highest level of biological filtration
  • Removal rates: (7 Log Bacteria 99.99999-percent, 6 Log Protozoa & Cysts 99.9999-percent)
  • 1 Million Gallons Guaranteed
  • 0.1 Micron absolute hollow fiber membrane inline filter
  • Use with a pump to prefilter, on a faucet adapter or inline in a hydration pack

According the the box and Amazon description, the filter should be able to treat 1 million gallons of water. This was a big reason for me buying it. In fact, if you do the math, 10 people could utilize 10 gallons (or 100 gallons total) of water per day from this filter and it would last 27 years. That’s a long time and a tall claim to make. Of course, it requires that you properly backwash the filter and care for it.

Anyway, before purchasing this filter, I choose to watch this YouTube video about it:

First Impressions

After receiving the unit, I was a bit surprised to see that it was slightly different that the video I watched (I had to watch it again to be sure) in that my unit included zip ties instead of hose clamps to secure the included plastic tubing to the filter housing. While disappointing it wasn’t a deal breaker; that said, I can see they’re skimping on costs, which tends to disappoint me. I also noticed that the color of the faucet adapter was different (mine is white, the video’s was black). While I have no idea if this makes any difference in quality or longevity, it did make me a bit suspicious. The rest of the supplied parts were as expected. Last, the manual, sadly, left a bit to be desired. It was one page front and back and half of it was situations they wouldn’t cover under warranty. Anyway, I wasn’t too worried about it as I expect to treat the filter well.

Intial Testing

My initial test was to connect the supplied faucet adapter to my faucet. To do so, I had to fit the plastic tubing over the filter housing end, which was all but impossible without first softening the tubing with a bit of heat as per the instruction manual. Just be careful when doing so was you can seriously deform the plastic if you’re not careful.

The supplied faucet connection is designed so that you’re supposed to be able to fit a variety of faucets sizes (it’s a molded plastic piece) but I was having difficulty attaching my faucet connector properly because it would stay without falling off. I eventually just shoved the entire faucet connector over the entire end of my faucet to get it to stay.

I then turned on the faucet about half way and found that the filter immediately began to spew water out the other end, as it should, but also began to leak quite severely out of the only seam in the filter housing. I took this as a bad sign and eventually reduced the faucet flow until the filter housing stopped leaking. So, mental note: make sure not to overburden the filter.

I then wanted to know how fast it can filter. I choose to clock how long it took to fill one cup of water. Using my faucet pressure it took about 35 seconds or so. Let’s just be conservative and say 1 minute per cup, which equates to 16 minutes per gallon (there are 16 cups per gallon) and roughly 4 gallons per hour. Over a 24 hour period that equates to 96 gallons. Happily, that works out to about the 100 gallons per day I had mentioned in the beginning… my how that works out. ;) Of course, this also depends on other factors such as how dirty the filter is and even altitude.

Other Options

Apparently, this is actually an older water filter model. They seem to have never models out such as this one:


I’m still relatively happy with my purchase. At less than $50 for this filter I wasn’t expecting greatness. I am a bit disappointed in the cost cutting measures and I am still a bit worried about the water leaking out the filter housing seam. That’s NOT filtered water–and it’s wasteful–so I would need to ensure I connect a good length of outflow tubing from the water filter to my “clean” storage water so that I do not risk accidentally contaminating my clean water if the filter housing leaks when I’m not aware of it.

Overall, I would say the Sawyer SP121 Just Drink Inline Water Filter will work ok for my intended use. I might choose to buy a newer model and maybe even more than one just in case one fails me.

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