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Reviews > Water Treatment > Filters > Guyot Designs TapGuard > Test Report by Brett Haydin


INITIAL REPORT - April 23, 2009
FIELD REPORT - July 07, 2009
LONG TERM REPORT - September 08, 2009


NAME: Brett Haydin
EMAIL: bhaydin AT hotmail DOT com
AGE: 36
LOCATION: Salida, Colorado, USA
HEIGHT: 5' 11" (1.80 m)
WEIGHT: 195 lb (88.50 kg)

I started backpacking in Wisconsin as a youth, being involved in the Boy Scouts programs. As a young adult, I worked at a summer camp leading backpacking, canoeing and mountain biking trips. I now generally take short weekend or day trips in rough, mountainous terrain, although I have extensive experience in the upper Midwest as well. I take one or two longer trips each year, where I typically carry about 40 lb (18 kg). I prefer to be prepared and comfortable, but I have taken lightweight trips as well.



APRIL 23, 2009

TapGuard and accessories
Manufacturer: Guyot Designs
Year of Manufacture: 2009
Manufacturer's Website:
MSRP: US$ 15.95
Listed Weight: Not available
Measured Weight: 1.6 oz (45 g)
Colors available: Tahoe Blue, Tangerine, Black
Color Tested: Black

Other details provided by manufacturer

  • Package contains a TapGuard unit and two replacement carbon filters, enough for 200 liters of great water.
  • Fits Camelback, Nalgene and most wide mouth bottles.
  • Removes 95% of Chlorine.
  • Save money, save the earth replaces hundreds of disposable bottles.
  • Carbon filter material made in the USA.

Product Description

The Guyot Designs TapGuard is a supplemental carbon filter for wide-mouth water bottles. The manufacturer claims that the TapGuard will remove up to 95% of Chlorine, iodine and other bad tasting chemicals from the water in my water bottle. The manufacturer is very clear that this product is to be used with a safe water source, tap water or otherwise treated water. The product comes neatly packaged in plastic and comes with the TapGuard and two carbon filter cartridges. Each cartridge is wrapped in a silver material and has a sticker stating that the carbon filter must be rinsed under a faucet for 1 minute prior to use.

The TapGuard stands 3 in (7.6 cm) tall and is 2.125 in (5.4 cm) in diameter. The carbon filter pouch is 2.25 x 1.5 in (5.7 x 3.8 cm) and fits into an opening at the base of the TapGuard with a hinge. The TapGuard is constructed of food-grade silicone rubber and has a smooth feel to it. It is quite flexible and is placed into the opening of a wide-mouth water bottle. In the top of the TapGuard there are two openings: one that allows the water to flow through the carbon filter and another that allows air to flow into the water bottle.


The TapGuard is straightforward and easy to use. Looking over the packaging that was included as well as the website, I am impressed with the commitment that Guyot Designs has made to reducing waste from using disposable water bottles. The packing clearly calculate that 400 plastic bottles, 65 lb (29.5 kg) of CO2, 2 US gal (7.6 L) of oil as well as US $500 are saved as a result of using this product! The manufacturer also claims that the product is Carbon Negative, meaning that the product is bundled with CO2 offsets to negatively impact green house gases.

Besides being a green investment I hope that the TapGuard will noticeably improve the quality of the water from my tap. The product seems well constructed. The rubber does have a slight rubber taste but it does not bother me at all it is so faint.


The instructions are very clear and easy to follow. It is important to note that the carbon filter cartridges must be rinsed first in order to activate the charcoal carbon filter prior to use. I did this for one minute and did not notice anything. I somewhat expected there to be some visible material rinsed from the cartridge, but I did not see anything. After feeling satisfied that I had completed this step correctly, I proceeded to insert the cartridge into the TapGuard. The image below shows the next consecutive steps for installing both the cartridge and the TapGuard into a water bottle.
Installing TapGuard
Installing the carbon filter cartridge and TapGuard

Once properly inserted, I tested out the TapGuard. One thing that I quickly learned is that I need to suck in the water much like a straw, albeit a large one! The water doesn't flow as fast as it would without the product, but it also pretty easy. Another trick I learned is there is a definite tipping point for the water. Because the TapGuard takes up a bit of space, it is hard to tell where the water line is, so I have accidentally tipped the bottle too far. The water can flow out the second opening and make an awful mess! There is just a little learning curve with this item.


So far I am really impressed with the TapGuard. I have immediately noticed a positive change in the taste of the water from my home. It is also really easy to use and I like the environmental impact that I can have while using it. I am interested to see if the taste of the rubber goes away over time as well as if I can get used to drinking from the TapGuard as opposed to directly from a bottle. That is what testing is for! Please check back in approximately two months to see how the TapGuard is doing.



The Guyot Designs TapGuard has been my constant companion over the past two months both at work and at play. I have taken four day hikes ranging from 6 to 14 mi (9.7 to 12.5 km) in mostly rugged, alpine environments. Temperatures have been between 20 and 85 F (-7 and 29 C) and in rain, snow and sunshine.

I have also opted to take the TapGuard with me on several backpacking trips, all of them in the San Isabel National Forest in central Colorado. Two trips were overnights backpacking trips while the other trip lasted three days. The trips were in similar conditions to my day hikes with the exception of the weather conditions; I did not encounter any snow on my backpacking trips!

My water sources over the past two months have been from several different sources. I changed residence approximately halfway through this testing period. My first location had water that had a strong taste of chlorine as well as high mineral contents in the water. You could actually see the minerals in the water from time to time! My new location is serviced by a well and also has a rather peculiar taste. Fortunately there is a water softener that helps, but the pipes to the kitchen sink bypass the softener. At work, I have municipal water that tastes rather fine to me.


I have to admit, I am rather pleased with the ability of the TapGuard to improve the taste of tap water. I definitely notice a difference in the taste of the water when used with tap water. It effectively eliminates the chlorine taste from my first location and in my new location I also find that the taste is markedly improved. When I used the TapGuard in the backcountry I was using a Katadyn Hiker filter. I did not notice any difference in the taste of the water on these occasions.

I have found the TapGuard to be a little awkward to drink from. I have lost track of how many times I have opened up my water bottle to take a drink and have the water dribble down my shirt! I find that if the water bottle is rather full and gets jostled around, this is much more likely. I would have hoped that I would get used to drinking from it, but it has taken some getting used to. Another observation I have made is that I do tend to suck the water through the outlet.

Installing the TapGuard has been very intuitive and easy to do. The product easily fits in the style of water bottles I use. It is possible to refill my water bottle without removing the TapGuard, but I have found it to be much quicker to do if I take the product out.

carbon filter
Broken carbon filter

I have some further concerns regarding the durability of the TapGuard. The photo above shows the failure of the carbon filter after about 3 weeks of use. I have had some problems with the lid remaining closed that holds the carbon filter in place. From time to time, I find the carbon filter sitting on the bottom of my water bottle. At first I regarded the problem as user error, but I have gone through great pains to ensure that I am securing the lid but the problem has persisted.

On one occasion, the filter cartridge actually broke and all the particles began to float around in my water bottle, as the picture illustrates. Since replacing the carbon filter, I have continued to notice the same issue from time to time. From what I can tell, the lid pops open particularly when I am hiking on steep downhills. In the areas I am hiking, I can lose as much as 700 ft (213 m) per 1 mi (1.6 km) of elevation. I presume that the constant jarring with each downhill step causes the lid to open and then the filter to float freely. The first time it happened, there were a few particles of charcoal floating in the bottom. However the problem becomes progressively worse so I believe the filter breaks down from this process. I will continue to monitor this problem to see if this happens again.

I noted in the initial report that the rubber had an odd taste. That problem is no longer an issue for me as I no longer notice the rubber taste.


Overall I am pleased with the TapGuard. It clearly makes an impact on the taste of the water I use. While I have developed some concerns regarding the durability as well as the learning curve, the product is performing well. I plan to continue using the product in conjunction with chemically treated water on an upcoming backpacking trip to see if there is a difference. Please check back in approximately two months to see how the TapGuard holds up after another two months of testing!



Over the past two months, I have used the TapGuard almost daily at work and while conducting my normal workouts. I have also brought it along on an additional two day hikes in the Sawatch Mountain Range of Central Colorado. These were fairly rugged hikes with over 3,000 ft (914 m) of elevation gain on each trip. Temperatures this summer have been exceptionally mild; never below freezing while on my day hikes and usually above 70 F (20 C).

I have also used the TapGuard on one more backpacking trip. This was an overnight trip on Mt Shavano in the San Isabel forest. I hiked a short 1.5 mi (2.4 km) to a great campsite I had previously scouted. The following day was an early hike to the summit of Mt Shavano and Tabuache Peak, both over 14,000 ft (4267 m). The terrain was both alpine forest and tundra with some loose talus, but a mostly solid trail. Temperatures were excellent with a high of 85 F (29 C) and an overnight low near 40 F (4 C). I used the TapGuard in conjunction with iodine tablets.


Two days after submitting my field report, the second carbon filter broke similar to the first. The pouch was lying on the bottom of my water bottle, this time a tangled mess of carbon particles and an empty mesh bag. Frustrated, I headed out to the nearest store I could find that carries the filters and bought some replacements. Throughout the test series the latch holding the carbon filter in place has repeatedly opened. This happens while hiking or even just while carrying the TapGuard and water bottle in my backpack around town. I believe that if there were some type of elastic "lock" this problem could be remedied.

I am pleased to report that the TapGuard really does make well water taste better! At least to me it does. I notice a significant difference in the quality of the water I am drinking and prefer to use the TapGuard with my water bottle for that reason. While backpacking these past two months, I took the opportunity to see if the TapGuard could improve the taste of iodine treated water, While I noticed a marked difference, the distinct aftertaste of iodine was still present.

The TapGuard itself is still intact. I have washed it a number of times during the test series and I see no signs of wear.


I really enjoy the quality of taste produced by the TapGuard over regular tap water. However my experiences with the filter compartment and replaced cartridges have left me unimpressed with this product as a whole.

Things I like:

  • Improves the taste of tap water
  • Easy to install and use
  • Can be used with a number of wide-mouth water bottles

Things that could be improved:

  • Filter compartment does not remain closed while in use. There could be a locking mechanism incorporated into the design.


Unfortunately I do not intend to continue using the TapGuard while hiking. While I enjoy the improved water quality, the continued problems with the cartridges makes this item too much trouble for my liking. I will continue to use the TapGuard at home and at work, as I do enjoy the improved taste!

I would like to thank Guyot Designs and the monitors at BackpackGearTest for allowing me the opportunity to test the TapGuard.

This report was created with the Report Writer Version 1.5 Copyright 2009. All rights reserved.

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