Let's Talk About Threads

Let's Talk About Threads

We get so many questions about threads; it seems funny that something so simple (from the looks of it) gets so much attention, but it does. So, to clear things up, maybe it is time to talk about those seemingly "simple" threads and add a little more info about the Vecto.

March 2019 update: Most of what is mentioned below relates to our 2018 Vectos as we kept adjusting the thread to fit a greater range of connections. The 2nd generation Vectos that we are offering work with practically any kind of 28mm female thread: all the Sawyer filters, HydroBlu, LifeStraw, you can use any cap, hose connection or anything else that has a 28mm female thread. The new Vectos have a stiff neck and a unique thread to allow a universal seal using mechanical torque.

When talking about threads, we mean the screw-like lips on the neck of the container (in our case, the Vecto) that connects with a cap or a filter for a perfect seal to prevent leaking. To take the Wikipedia definition (for a screw cap): "A screw closure is a mechanical device which is screwed on and off of a "finish" on a container. Either continuous threads or lugs are used. It must be engineered to be cost-effective, to provide an effective seal (and barrier), to be compatible with the contents, to be easily opened by the consumer, often to be reclosable, and to comply with the product, package, and environmental laws and regulations. "

Despite this apparently simple definition, things are not that simple: bottle threads are not standardized but follow more of a recommended guideline. Not only are they not standardized, threads for 28mm threads can fall under the set 28mm group (Alcoa, Orbist or PCO) or under the size ranges (SP400/410/415). 

To give a quick explanation, here are the main groups:

SP Threads

SP threads are recommended threads for PET (Polyethylene terephthalate) bottles in a variety of neck sizes, are meant to allow for easy closure, and have similar dimensions. In this group, there are SP400, SP410 and SP415. These are the most common threads, which have interchangeable caps that really only differ in the length of the neck (aka, depth of the cap).

In this group are also SP425 and SP430, which have a slightly different thread pattern and are usually used for a higher seal item.

The illustration below explains these threads:

Dedicated 28mm Threads

This group of threads was developed specifically for what we know today as soda bottles. There three main groups: two by Husky that are either for flat water (Obrist) or pressure top (Alcoa), and one by ISBT (International Society of Beverage Technologists). The ISBT threads are the most common so I'll only explain those:

The ISBT threads are used very widely for any pressure threads since they have a non-continuous thread (they have grooves) that are offset to allow an excellent seal.

The ISBT threads differ in where the point of connection to the bottle is (depending on bottle shape) and ranges from 1810 to 1823 and 1881, each with a slightly different thread shape. Many of the pressurize soda bottle use this thread as it provides an excellent seal.

To give you a better idea and perhaps offer some confusion, here is what a thread spec sheet looks like:

Now, Back to the Vecto

All these boring technical stuff has a point - we wanted the Vecto to work well with as many threads as possible. Despite the "28mm neck" claims of so many filters, in reality, they often end up having different threads. Even more frustrating, the thread can sometimes be different for each product. To solve that, we opted for a hybrid of threads to provide the most options for you when in the field: The Vecto uses thread shape from the ISBT PCO 1823 and fits them on the PCO 1817. This allows it to use the pressure seal of the PCO while working with SP threads (that are thin) like the PCO 1823.

Just to give some context, here are some of the threads out there:

  • Cola bottle: PCO 1881
  • Old Cola bottle: PCO 1810
  • SmartWater bottle: PCO 1817
  • Sawyer collapsible bottle: SP 415
  • Platypus bottles: SP 400 (old), SP 410 (new)
  • Evernew bottles: SP 415
  • Sawyer mini filter: SP 410
  • Sawyer Squeeze filter: SP 415
  • HydroBlu Versa Flow: SP 425

The above makes you wonder, why do the SmartWater bottles work so well with the Sawyer filters but not the HydroBlu? Simple: the PCO 1817 has thicker threads that won't fit well into the HydroBlu's thinner grooves. This is why we used the thinner threads of the PCO 1881 on the 1817 shape, so they both fit!

We hope that wasn't too confusing to you and if you really want to dig in dipper into the world of threads and tolerances, here are two more resources:

ISBT Thread spec

Standard Specification for Dimensions and Tolerances for Plastic Bottles

Last Note About Threads and Vectos

The one thing we have heard the most from you is that you find the Vecto's threads to be too soft to get a good seal with some filters, mainly the Sawyer Mini. The reason for this problem is that the Mini has the oddest thread of them all (it works well with old soda bottles) but works well with everything else. To solve this, we are increasing the density of materials on the neck so you can use more torque to seal the Mini on properly.

All available Vectos are now updated according to your feedback: they feature a stiffer and longer neck that allows all filters, caps and hoses with a 28mm thread to connect securely. We are proud that we can make a product that actually fits everyone's needs.


  • Dave

    Does anyone make a plastic threaded plug with the water bottle thread on it? I would love to be able to leave the Sawyer coupler on the clean end of my filter and screw in a plug to keep that end of the filter from becoming contaminated when I put the filter into my ziploc bag after use, and it has “dirty” water on the outside. It’s a pain to have to take off the coupler, and put the Sawyer cap back on the clean end. I cannot seem to find 28 mm 6 TPI plastic plugs anywhere in the marketplace. If you make it, I would buy it.

  • Anonymous

    Hi Adam,
    Check out the Sawyer in-line connectors. We usually have them in our store (due in soon) but they can also be found on Amazon or the Sawyer website.

  • Adam W

    Purchasing the 2020 Vecto 2L, 28mm. Any suggestion on what specs to search for, for an adapter to connect to the bag and then to an 1/4" ID hose? Looking to put a hose between the bag and a filter. Trying 28mm to 1/4" ID barb doesn’t yield great results. Thanks!

  • Lauren

    Hi Kent, you have the 2018 model. I will follow up with you via email.

  • Kent Stuart

    You make a very good product. However, I just recently purchase three bladders from you in February 2019. Do I have your new product or last years model threads? I mainly use the sawyer filters. I am currently showing your product to the county SAR team. Thank you.

Leave a comment

Please note, comments must be approved before they are published

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.