How do you use a Millbank Bag? And what are Millbank Bags used for?

by Elvis Jai Closs on July 17, 2021

What is a MillBank Bag? 

A Millbank Bag is a water filtration device, designed to filter out all of the detritus from the water. These detritus include sand, mud, silt or other suspended particulate matter.

Removing all of the detritus before further sanitation is extremely important. Even if there are no waterborne diseases present, turbid water will irritate and cause damage to your digestive system. In addition, turbidity can reduce the effectiveness and lifespan of other water sanitation systems including the well recognised Life Straw, for example. 

However, a Millbank bag will not filter out pathogenic organisms, unless those organisms are attached to the detritus that is filtered. This is why additional forms of sanitation are required, including chemical or heat sterilisation. If your water source is already clear, and has no detritus present then there is little advantage to using the Millbank bag. Although, few of us our lucky to find such water sources out in the wilderness!

How do you use a Millbank Bag?

1) Start by thoroughly soaking and massaging the bag underwater. This process will help saturate and loosen the bag's fibres. Otherwise, it can take hours for the water to filter through the bag. 

2) Fill the bag to the brim, hang the bag up, and let the water drain out till the water is level to the black-white transition line (do not collect this water). This step ensures that you are only collecting the water that has drained on the bag (not excess water on the outside of the bag) from the saturation process. 

3) Then, when the water level meets the line start to collect the water that is draining through. In my experience, filtering a 1L bottle takes around 20mins, although sometimes it is a little faster. If sanitising over the fire, it makes sense to collect the water straight into a metal pan or cup. 

4) After the bag is empty, wash off the bag, fold it up and tuck neatly away! The bag will need cleaning from time to time. This is because the build up of detritus can cause the filtration process to slow as it blocks the passage of water through the bag. 

5) Sterilise! Remember, the Millbank bag is designed to aid further sterilisation, not to purify water completely.

The Forest Fundamentals Millbank bag

The Forest Fundamentals Millbank Bag uses the same dimensions and materials as the original British Forces bag. We have made some minor changes however - we have replaced the cord with a stronger, 550 updated Military Grade survival cord that incases strands of parachute cord, snare wire, tinder rope and fishing line. We have also updated, the design of the bag to look a little more modern and sleek. You can view our handmade Millbank bags here

Please be careful buying original British Forces Millbank bags! Today, mostly all Millbank bags being sold are surplus - they have seen years of use, and were most likely used to filter oil and other nasty chemicals. It is better to play it safe, and checkout our update Millbank bags!

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