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Back Flushing a Water Filter

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south of Winnipeg
Our Platypus filter clogged on us for the first time yesterday. Fortunately it was the last day of the trip. We had sort of been expecting it as flow had slowed and the lake we on seemed to have quite a high sediment load. Made up a connector this morning to attach the outlet hose to the outside tap. Once the water started running a very satisfying blast of brown muddy water was expelled from the inlet side before running clear. A quick test with some clean water found that the filter now runs like new.

Thinking back, I'm not sure I have ever back flushed this filter since we bought it at least five years ago, so feeling somewhat guilty now.

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That looks like heavy artillery! I can believe that you get good pressure with it. We carry a large capacity (+/- 150 ml) syringe that I picked up somewhere. It fits into the outflow side of our Sawyer filter getting a pretty good seal. We back-flush every other day or so on a trip.
 
Yes, I really should remember to bring the syringe along, I have one that came with the Sawyer system we have for backpacking. I'd like to find an adapter to fit the MSR Dromedary bag we have so that I could use that to back flush the filter.
 
I have a Platypus and the instructions say to back flush every 20 liters, I have a 4 liter bag with it, so every 5 bags ... a single filter lasts a long time if you do this and also follow the instructions for storing with a bleach solution so you don't get bad gunk growing in there.

Brian
 
I only bought the filter unit not the whole set up so don't remember any instructions. The interesting thing was that all our filters clogged; a brand new Cnoc, a used but well maintained Sawyer and our Platypus unit. I back flushed our Sawyer mini last night, I have always backflushed this one with syringe after every trip, and was able to flush some gunk out of that too. Seems to have the potential to rejuvenate old filters.
 
I contacted Sawyer regarding the reduced flow rate of my water filter and wondering if I need a replacement cartridge (which is no longer available). Below is their response. I thought I share it with you because I thought it was helpful.


It sounds as though your filter is just blocked, either from particulates or minerals. With proper cleaning and if stored in a cool dry place out of direct UV light, your filter should last a lifetime. More often than not, the filters that are mailed to us are restored by our engineers using the process below...



A blocked filter can almost always be recovered by soaking the filter in hot water (not to exceed 135 F) for an hour or so, and then backflushing several times with hot water as hard as possible. The trick to a successful backwashing is to be very forceful with the process.



Water will always take the path of least resistance, so in order to fully flush out the filter and restore its flow rate, make sure you are exerting as much pressure as you can, especially during the first couple of passes. If that doesn't work and your flow rate is still slow, your water source might be mineral rich, so we would suggest soaking it in vinegar for half an hour or so, and then repeating the process with hot water backflushes.



To sanitize the filter, we'd recommend using a weak bleach solution (one capful of bleach per Liter of water). Slosh the weak bleach solution around in your pouch and run it through the filter. After the pouch and filter have been sanitized, let the filter sit upright with sufficient ventilation to dry out before storing the filter in a cool/dry location away from direct sun exposure. Some tips:

Trying to filter water through a blocked filter will always make things worse.
Backflush, backflush, backflush,……
A second or third soak may be necessary. The more you do this, the more recovery you will achieve.



If after trying this your filter is still blocked, we would be happy to have one of our engineers take a look at your filter. Note: please check with us to see if we are receiving them in the months from October through May, due to possible freezing conditions in various parts of the country.



Please safely pack and send it in a properly sized box with sufficient packing material to avoid physical damage in transit. Envelopes and utility mailers will be returned. Include either a note stating the issue or a printed copy of this email chain.



Packages can be sent to the address below.



Sawyer Products

Filter Review
605 7th Ave North
Safety Harbor, FL 34695



Hope that helps!

 
Good to have that info. from Sawyer. Our Sawyer mini (and a friends Platypus filter) plugged up again on day two of a more recent backpacking trip. We knew as soon as we looked at the lake and the algae floating in the water column that we would likely have trouble. It was quickly cleaned by back flushing using some of the clean water we had by inverting and then squeezing to flush. Gave it another flush through with the faucet adapter when we got home.
 
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