Question for those who are gravity filtering…

When filtering: Dirty water bladder –> tube A –> filter –> tube B –> clean water bladder.

When drinking: clean water bladder –> hydration tube –> bite valve

Jacob:

I don't and I wouldn't recommend using "Tube A" as hydration tube. Is that your question? And I wouldn't because I don't think running clean water through that tube once or twice is enough. I would want to use chlorine to purify — and that's a whole another hassle.

Assuming you are happy with the total length (or height) from Dirty bladder to Clean baldder — can you use a shorter Tube A and a longer Tube B — keeping the total length more or less the same? Because with an appropriately longer Tube B — you can use that as your hydration tube as well — without risk of contamination.

ADDENDUM:

I'm wondering about the reason for wanting Tube A to be longer. Jacob, if you are thinking that a longer Tube A would mean a longer "free fall" that will generate a greater force when the water hits the filter and thus resulting in a faster through-put — I really haven't noticed any practical difference at all — as compared to a shorter length Tube A.

I have to agree with Ben. This is the system I use when I have both my gravity filter and hydration bladder.

Ben, your description above is what I use (or have set up anyway). I just put together my system then it came to my attention that some people re-use the tube (tube A) which seems unnecessarily risky to me. I'm just polling the audience.

I see — although I can't imagine why anyone should choose Tube A over Tube B. But if there are, this thread should be helpful.

"ADDENDUM:

I'm wondering about the reason for wanting Tube A to be longer. Jacob, if you are thinking that a longer Tube A would mean a longer "free fall" that will generate a greater force"

In the first days of gravity filters thirty years ago, the filter element was a new VW fuel filter, and it was difficult to get water to flow through it unless you had a 15-foot water head over it. I have no idea what the pore size was on the filter. The point is that if your filter is tight enough, you will need a lot of pressure to get the water to flow, and that means a longer tube. Now, I don't think that we use filters with those kinds of pore sizes, so I don't think that the tube needs to be so long.

–B.G.–

The topic of contamination just came up in another thread. Basically, the OP asked "how many baddies does it take to get me sick?"

The consensus on that thread was if you're in relatively clean water areas, just a simple flush of the dirty tube with clean water will be enough to rid most of the germs out. There just wouldn't be enough to get you sick. However, use that advice at your own risk!

Ben, it wasn't a question of choosing to re-use the dirty tube ("tube A") when carrying two tubes, it was a question of carrying a only single tube (i.e. the tube from your hydration system).

Bob, I agree the dirty tube probably doesn't need to be very long. I have only just switched to gravity filtering and don't have enough extended experience with my filter (Sawyer SP122) to know what length will work best. Right now I've got a length of tubing that's about the same as the hydration system.

I think more than anything I'm going to look for lighter tubing as the Platypus tubes are not all that light. I personally won't risk going to a single tube setup to save an ounce.

"I think more than anything I'm going to look for lighter tubing as the Platypus tubes are not all that light."

Yes, I think that is the right idea. My longest tube is about two feet long, but it is not as heavy as the real hydration tubes. I think mine was from a shower kit, so the connectors are right.

–B.G.–

"I think more than anything I'm going to look for lighter tubing as the Platypus tubes are not all that light. I personally won't risk going to a single tube setup to save an ounce."

Don't see how you can have a single tube set up, Jacob! As you described, you've got 2 tubes — tube A and tube B. The question is which one to choose for double duty as hydration tube, so you can avoid carrying a third tube, correct? It seems pretty obvious that between the two, A and B, one would choose B — the clean tube, to "multi-use" as hydration tube. And to put on the pack and position the bladder to measure out the correct length first — as hydration tube — before cutting. And once Tube B's length is determined, than one can determine the desired length of Tube A as part of the gravity set up.

A few years ago, I spent time looking at water containers, water treatment options, and hydration systems simultaneously — to make sure I end up with a compatible "system". YMMV, but taking bladder and all into account, I ultimately chose Platypus bladders and tubing for its overall light weight. The Playtypus hydration tubing itself may not be the absolute lightest, but I like how it works with my AquaMira Frontier Pro filter. Whatever the system, I recommend that people decide and shop for all these components at the same time.

"Whichever outcome, it's good to shop for all these components at the same time."

I think that is why we have REI stores.

–B.G.–

Alas, no, REI doesn't carry the AquaMira Frontier Pro. But that's fine… REI prices are rarely competitive. I'll pay REI's price preimium if I utilize their expertise and/or desire their unconditional warranty. But otherwise, for pricing, there are often better alternatives. Anything else, Bob?

Nothing else. It is just that REI tends to have a good selection of this kind of water stuff. So, if you need to hold it in your hands and feel it, that is one store to start with. It is difficult to judge the flexibility of a hose when shopping online.

Yes, REI prices tend to be a bit high. But, if it is only some $5 – $20 item, there is little point in driving back and forth across town (with gas prices as they are).

–B.G.–

Hi Jacob,

I got the Platypus Gravity Filter – it comes in the following setup.

4 liter dirty water bladder –> dirty tube –> filter –> clean tube –> 4 liter clean water bladder.

Once you filtered the water, you detach the clean tube from the filter and fill the water into your water container. In our family we use Platypus Bladders as water container.

I have modified our gravity filter setup and eliminated the 4 liter clean water bladder and the clean tube. I use the CamelBack Filter Adapter. It comes with three pieces. One is attached to a very short piece of tube at the clean end of the filter. One has a valve and I put the Platypus mouthpiece on it. The third is attached to the end of my Platypus bladder’s tube. Now I can disconnect the mouthpiece and connect the bladders’ tube to the clean side of the filter with a simple click. All our bladders are set up like that. We can connect our bladders to the gravity filter without having to take them out of the pack and we save the weight of the 4 liter clean bladder and its clean tube.

Manfred

"Don't see how you can have a single tube set up, Jacob! As you described, you've got 2 tubes — tube A and tube B. The question is which one to choose for double duty as hydration tube, so you can avoid carrying a third tube, correct? It seems pretty obvious that between the two, A and B, one would choose B — the clean tube, to "multi-use" as hydration tube. And to put on the pack and position the bladder to measure out the correct length first — as hydration tube — before cutting. And once Tube B's length is determined, than one can determine the desired length of Tube A as part of the gravity set up."

To reiterate, I never said that anyone carrying a setup like you described, and I currently have, would choose to use a dirty tube for their drink tube. This would require disassembling the whole works and switching the tubes around; that's just madness.

Having said that – yes a single tube setup is possible, you're not thinking outside the box ;) One way is to remove the drink tube cap (with tube attached) from hydration bladder, screw it onto dirty bag, pull bite valve off other end and replace with filter. Point filter output into clean water bottle.

Ok, so that's a major PITA. Another way is to use the quick disconnect fittings supplied by Sawyer to make the tubes and bite valve couple/decouple easily. The new SP122 requires the use of at least 2 of these fittings anyway (they weigh 0.10 oz). To be semantically correct, yes, there are still 2 tubes however one of them can be extremely short. If the short tube is on the clean side (to maximize static head), then presumably the drinking tube is on the dirty side. If the other way around, such as shown in Tony Wong's review of the Sawyer filter, contamination is not an issue unless one decides to put that short tube in their mouth for some odd reason… however this produces the least amount of static head.

Hi Manfred. Hope you and the family are doing well.

My setup is somewhat similar to yours. I have the 4L Platy and had already been using the 2L Platy Hoser hydration pack. I added to this the Sawyer "3-Way" filter plus a Platy drink tube kit. I don't have a dedicated clean bag and will filter directly into the hydration pack. By using the supplied quick disconnect fittings I can easily decouple the bite valve and connect the Sawyer filter in its place.

I have only just put this together and tested around the house, but it seems convenient and fairly light weight.

Surprisingly the two Platy tubes weigh a total of 3.5oz (bare tubes, no fittings). The whole setup (filter, hydration pack, dirty bag, both tubes, all fittings) weighs a total of 11.8 oz on my scale. I'm hoping to get it down to an even 10oz by replacing the stock Platy tubes with something a little lighter, and possibly shortening the dirty tube just a little.