A few grams here, a few grams there… in search of the perfect water filter

This post is a little different from my normal, if occasional … in search of posts. Whereas I would normally have purchased the gear items that I have tried out and selected what works for Three Points of the Compass, I must confess to having very little experience of different water filters for backpacking use, while this post looks at a product that has yet to even be released upon the market.

For the majority of my backpacking trips in the 1970s and 80s, I used chemical treatment if I felt that I had drawn from a dodgy water source. After-taste was a problem and I was never really comfortable with putting additional chemicals into my body, certainly not in the quantities required to maintain decent hydration. Iodine for example, is not recommended for prolonged usage. Walking into the 1990’s I moved away from chemical treatment such as iodine and chlorine when backpacking and never returned. Such treatment suits some people, just not me. I concentrated instead, on looking for safe municipal water supply or bottled water. Potable, or safe to drink, water is usually fairly easily accessible in the UK, or at least it used to be. Contamination of original sources is on the increase, reported instances of both Giardia and Crytosporidium are on the rise. Chemical run-off (pesticides and fertilisers) in some districts has reached alarming levels.

There are many pathogen that thrive in both damp and wet conditions. Bacteria is probably the largest risk. Escherichia coli and Salmonella sp. are well known. The fairly large protozoa, such as Giardia and Crytosporidium are easily caught by most water filters. Viruses are small, very small. Therefore few, if any filters are going to remove them. Treatment by UV light, boiling or chemical treatment is usually required for these.

There are various types of filter, or ways that you can use a filter- pump, squeeze, in-line, straw, gravity. My preference is for a filter that can be used in any of the last four methods named. For the past few years I have been using, if only infrequently, a Drinksafe Aquaguard Micro 3 in 1. This is a perfectly good filter. I have had problems with getting a decent seal between the two main body parts, but Giles, the proprietor of Drinksafe has delivered prompt reply to emails and supplied, free of charge, replacement O rings etc. The filter itself weighs 105g, all of the various parts associated with it (including storage cup that need not be taken) weigh 220g. For my most recent trip carrying this filter, some 100 miles along The Ridgeway and side trails, where I never even need to put it to use, my ‘squeeze’ kit weighed 239g.

Because this is such an effective filter, I have never felt the need to migrate to the Sawyer filter. I couldn’t see that it offered any real advantage other than a better sealed body and thinner dimensions. I have toyed with the idea of inserting an in-line carbon filter, of the type found for fish tanks etc. alongside my current filter. These filters do a lot to not only remove further impurities, but also improve the taste of water. But to be honest, I couldn’t be bothered with the faff. There are other manufacturers of decent water filters, MSR amongst them, but again, I saw no real difference in their products. A ‘step change’ in design and effectiveness had yet to occur.

I almost did make a change in 2014 when I saw a piece by Sintax 77 on the Renovo Trio water filter, but again, while it appeared to be a decent product and I was drawn to its 0.05 micron filter (over the 0.1 of the Sawyer) pore size, it wasn’t offering sufficient to persuade me to part with my hard-earned cash. I had noted that the Trio came with an inbuilt carbon filter, a company to keep my eye on I thought.

Getting it right- MUV prototypes

Getting it right- MUV prototypes

And what do you know- it appears that Renovo have been working on their product and combining a lot of the features I wanted to see. Good level of filtration, reduction in thickness (over my Aquaguard), combination of a pre-filter and carbon filter, ability to use as in-line, squeeze, gravity, straw… hmm.

The different detachable sections of the MUV

The different detachable sections of the MUV filter and their purpose

The product is still in the design stage. It is not yet on the market to purchase (more on that later). The Renovo MUV comes as three main body parts that can be included or excluded as wished via the simple twist and lock connectors. In addition there is a detachable mouth piece (straw top) and cap. It has a well designed body that resists rolling. Prototypes were made of 3D printed materials, the end product will be injection moulded with rubberised grips for slip prevention. The weights of the final product are uncertain as yet but I enquired about estimated weights and was told by Daniel Beck, President of Renovo Water:

“The 3D printed prototypes weights for the modules are as follows: MUV 1 – Activated Carbon less than 2 oz, MUV 2 – Hollow Fiber less than 3 oz, and the MUV 3 – Nanalum less than 3 oz. We don’t anticipate much difference in weight either up or down from the prototypes, but it will be dependent on the final materials selected for the production run. As a comparison for you, coupling the current MUV 1 and MUV 2 prototype modules together is about the same weight and length as a Sawyer Mini.”

Cross section of component MUV sections

Cross section of component MUV sections

There are three separate filters on the Renovo MUV adaptable water filter: MUV 1- Activated Carbon, MUV 2-Hollow Fiber Membrane and MUV 3- Nanalum.

There are some bold claims made as to the effectiveness of the MUV 3 filter. Renovo state that it will remove some viruses, including Hepatitis A, Polio, Typhoid and enteroviruses. I hadn’t heard of Nanalum but Renovo inform me that:

The technology used in Nanalum was developed by NASA as a way to reuse waste water on the International Space Station. Nanalum works through electro-absorption and is manufactured with non-woven highly engineered water filter paper which is also impregnated with Granular Activated Carbon (GAC). The Nanalum module has a strong positive electrostatic charge when wet. Like a strong magnet, the positive electrostatic charge of the Nanalum attracts and traps organic contaminants

Marketing Director Kirk Sample demonstrating the MUV as a drinking straw

Marketing Director Kirk Sample demonstrating the MUV as a drinking straw

I do like the inclusion of a pre-filter to remove the large particulate matter that may be present in water. It is, of course, possible to strain water initially through a shirt, bandanna, coffee filter or similar. But who amongst can really be bothered? Just a bit more hassle, so usually dismissed, which means the filter clogs up, which slows throughput until back-flushed. Which means that some means of back-flushing needs to be carted along as well. It is for that reason that I was never drawn to the Sawyer Mini- the considerable number of reports on its rapidly diminishing flow rate could not be ignored. At least not by me.

Use as an in-line filter

Use as an in-line filter

I am not over keen on the mouthpiece that is shown on the prototype Renovo MUV, but there is also the option to purchase detachable in-line connectors that can replace the shaped mouthpiece shown above. The company has stated that all the component parts that require replacing over time will be available for after sale purchase. MUV 1 has an indicated filter life of up to 150 gallons (682 litres), MUV 2  a filter life of up to 100 000 gallons (454 609 litres) and MUV 3 an expected filter life of up to 90 gallons (409 litres).

Interestingly, the company have not simply released this straight onto the market. Instead, they launched a Kickstarter campaign with a view to having it fully funded by 23rd June 2016. They achieved that ambition within 72 hours of launch. There are (at the time of writing) various rewards available with just the one, frankly unappealing, stretch goal, again achieved.

So, this post is not intended to be an advertisement for the MUV filter. It will stand or fall on its own merits. For me though, I believe that this exciting development, with the flexibility to alter the filter to suit an individual’s own needs and wishes yet still provide leading standards of water filtration, means that the Renovo MUV Adapatable Water Filter may soon represent the best lightweight water filter available for backpacking purposes. It is for this reason that Three Points of the Compass has become a backer of Renovo’s Kickstarter campaign, I wish them well and look forward to my filter.

The MUV filter will screw directly onto a standard 28mm drinks bottle

The MUV filter will screw directly onto a standard 28mm drinks bottle

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