HydraPak have produced a number of accessories to fit their wide neck bladders and bottles. Three Points of the Compass has a glance at two of these, that permit a 28mm threaded water filter to be fitted.

The wider 42mm neck on many HydraPak products enables them to be more easily filled with water than narrow neck options. The US company have produced a number of Plug-N-Play accessories, what they call ‘hydration upgrades’, two of these can be combined to enable popular filters with 28mm threads, such as the Sawyer Squeeze, to be used with the durable TPU HydraPak water containers.

Plug-N-Play Cap:

This is a direct replacement for the standard screw on cap on a HydraPak Seeker, Flux bottles and Flasks. The Plug-N-Play Cap weighs 18.22g and comes with a 4g debris guard with a 230mm length of thin shock cord with a loop at one end. The loop would be passed through a shoulder strap’s daisy loop or similar and hang free when not clipped into the Plug-N-Play Cap. The dirt guard is not an essential part of the Cap and can be excluded if wished but it is best to keep dirt out of the open cap as this could potentially jam up the workings.

The top of the cap has three raised edges that are turned to release any accessory clipped into it. This is more easily achieved using both hands. The twist action release is internally tensioned and the nozzle of whatever accessory has been fitted, once released, is pushed out with a small stainless steel spring. I am not over-enamoured with the complication of this twist cap and can see potential issues with water contaminated with floaters causing debris to get stuck and causing leaks in the cap. This could be easily circumvented by prefiltering water into the ‘dirty water bladder’ through a bandanna or similar, but this is yet more unwanted faff and does away with the advantage of having an easier to fill 42mm neck.

One of the images above shows the filter apparently being screwed onto a Filter Adapter already clipped into the Cap, this is the incorrect way to use this. The Filter Adapter should be first screwed onto the filter, then clipped into the Plug-N-Play Cap. This circumvents (unfiltered) water being lost from the water holder. Note that this clipped together set-up can also be used as a hanging gravity system.

Filter Adapter:

This is a simple little plastic adapter that clips directly into the Plug-N-Play Cap. It has a 28mm male thread so enables a filter with that thread diameter to be screwed on. It can be left attached to the filter, or remain plugged in to the Plug-N-Play Cap and a bottle lid screwed on to stop it getting dirty and water exiting. The Filter Adapter weighs 6.38g. Ideally, it should be left screwed on to the inlet end of a Sawyer water filter until it is plugged into the HydraPak Plug-N-Play Cap.

The Filter Adapter is a simple moulded piece of plastic with an O-ring at the nozzle end to prevent leaks. There is a small hole in one of the side fins, but this is too small for even a mini-biner and a loop of cordage would be required to hang this off something to stop it going missing.

If the Plug-N-Play Cap isn’t turned fully to disengage the nozzle, it can become stuck half-way in/half-way out, so a decent positive twisting action of the Cap has to be done to enable a decent ‘pop’ out of the Adapter.

The Plug-N-Play Cap and Filter Adapter together weigh 24.6g (25g), or 28.6g (29g) with the dirt guard and tether. I would have preferred it if HydraPak had released a one piece adapter from wide neck to 28mm male thread rather than this needlessly cumbersome two-piece affair as I have no wish or need to attach anything else to the cap.

Three Points of the Compass has previously looked at a simple hack of using a redundant BeFree filter that enabled the same switch down from 42mm to 28mm threads. That weighed 14.5g and was a reasonably good solution, but did, of course, require a donor filter.

Gear talk: converting a 42mm neck HydraPak bladder to fit a 28mm water filter- the hack

It should be noted that not all 28mm threads are created equal. Thread pitch can differ and not every 28mm threads happily mates with another. There is no issue with any HydraPak thread correctly screwing on to another HydraPak product. Three Points of the Compass is a bit of a fan of the various TPU HydraPak bottles, flasks and bladders and I have shown a number of combinations here utilising water containers with capacities from 500-2000ml. There are plenty of other options in addition to these, not least the wide mouth Cnoc bladders, just be aware of potential issues with thread pitch.

It should be noted that there is nothing unique about the push fit connector that is inserted into the Plug-N-Play Cap. Back in 2016, long before I moved on to my favoured BeFree filter, I was using an Aquaguard Micro water filter from Drinksafe. I think the last time I used that particular filter was when I backpacked the Ridgeway, though I still have it knocking around in a gear locker. With male and female quick disconnects, purchased from a DIY or plumbing shop at the time, this filter can also easily connect to the Plug-N-Play Cap. Sawyer have also sold these connectors themselves as Fast Fill Adapters for Hydration Packs.

The Plug-N-Play Cap is not confined to just the Filter Adapter and as seen, can be used with other accessories, though there not many of these available from HydraPak. They include a Camp Tap, which is a small tap on the end of a short length of hose, or any of the HydraPak tube kits can also be plugged in. HydraPak’s own 28mm Inline Filter can be plugged in, doing away with the need for the Filter Adapter, or they sell a couple of their own filters, one that can be screwed onto a 28mm thread and another with a 42mm thread.

As previously mentioned, with such a small range of compatible Plug-N-Play accessories, I would have preferred it if HydraPak had simply released a straightforward 42mm to 28mm step down adapter, but they didn’t, so we are stuck with this two piece solution. While neither of the two accessories are particularly expensive, it is still additional cost over buying a bladder and a filter. Something else to fiddle with, something else to misplace, or worse, something else to break. But, it is a (sort-of) solution for those wanting to marry a filter such as the Sawyer with a HydraPak type wide-mouth bladder. Sadly, it is not something that Three Points of the Compass is likely to permanently integrate into his hydration and filtration set up.