Guest - Not logged in 

Reviews > Water Treatment > Solar > Puralytics SolarBag > Test Report by joe schaffer

Initial Report
by Joe Schaffer

May 21, 2015

NAME: Joe Schaffer
EMAIL: never2muchstuff(AT)yahoo(DOT)com
AGE: 67
HEIGHT: 5'9" (1.75 m)
WEIGHT: 175 lb (79.4 kg)
HOME:  Hayward, California (CA) USA

    I frequent California's central Sierras, camping every month with a goal to match my age in nights out each year; about half the time solo. As a comfort camper I lug tent, mattress, chair, etc. Summer trips last typically a week to 10 days; 40 lb (18 kg), about half food related; about 5 miles (8 km) per hiking day. I winter camp most often at 6,000 to 7,000 ft (1,800 to 2,000 m); 2 to 3 nights; 50 lb (23 kg); 1 to 4 miles (1.6 to 6.4 km) on snowshoes.
Puralytics bag
The Product:
        Manufacturer: Puralytics
        Distributor's web site:
        Product: Puralytics SolarBag
        Received: 5/16/2015

MSRP: $99.99 US

My measures:
    weight: DRY 3 7/8 oz (111 g)
    weight: WET not wet yet
    height: 15 1/4 in ( 38.74 cm)
    width: 9 9/16 in (24.25 cm)
    min. thickness: 2 5/8 in (6.67 cm)
    weight: DRY:  4 oz (105g)
     capacity: 3.5 L
KEY FEATURES: The product claims sunlight activates a "nanotechnology mesh" removing all viruses, bacteria, protozoa and toxins without batteries, chemicals or filtering. This is the only product I have that claims to remove--as opposed to neutralizing--everything but the wet.
    This is a nearly-clear non-BPA plastic bag with a common water bottle-type mouth and closure; containing a somewhat-honeycomb-looking flat mesh occupying most of the flat dimension. The 2 5/8 in (6.7 cm) screw cap affixes to the bag via a plastic retainer strap. The product includes a 4 1/4 x 4 1/2 in (10.8 x 11.4 cm) white bag with an elastic hem at the open mouth to serve as a pre-filter. It looks much like a heavy duty coffee filter; with the elastic gripping the mouth of the bag--well thought, I think. The bag's flat seams are about 3/8 in (10 mm). The top corner opposite the mouth is bonded in a triangle of about 4 x 4 3/4 in (10.2 x 12.1 cm) and holds a large plastic grommet with a 1 1/2 in (3.8 cm) hole.

    I've tried many types of treatments, including wishing, filters, chemicals and UV. I don't tolerate chemicals. Filters can clog, requiring avoidance of water with algae or suspended particles (muddy). UV doesn't work in cloudy water, and I don't trust batteries. Wishing worked for so long I fear the odds of that continuing to be effective have grown dangerously long. I find no perfect treatment for the types of circumstances I routinely encounter.

    Here is a product that doesn't pump, drain, ask the user to consume noxious chemicals or require technology involving batteries. How can I sleep knowing I've gone so many years without it! Perhaps the answer will be that I can take a long nap waiting for it to work. The manufacturer claims 2 hours in bright sunlight; up to 6 hours if cloudy water or sky. There's supposed to be some kind of indicator that the treatment is done, but I don't know what it is. Thirst?

    Having no way to assess the technical merits, I can only say the bag appears to be well constructed.  I wonder how long the pre-filter will last, and testing may tell. The manufacturer notes an unused shelf life of 7 years for the system, but makes no mention of how long it may last wet. The claim is that it is reusable hundreds of times. If that works out, a bit of math suggests 200 uses of 3.5 L (3.5 qt) = 700 L (700 qt) of purified water for $100 = 7 cents a liter (quart). That's incredibly cheap. One presumes the claim shall prove out. I doubt the bag will survive hundreds of roll-ups and a couple thousand hours of exposure to sunlight, but that in itself does not dispute the output claim.

    Though I'm not going to read any directions, I did accept the manufacturer's invitation to wallow through the scientific reports on the product. I accept without reservation that the product is effective when used as directed (which I'm not going to know).

    At a quarter-pound (113 g) for a treatment system I have to be impressed. Waiting for it to work may require a protocol adjustment, during which time I will suffer the weight of a UV product. Wait time should be no issue on slack days. Perhaps if I can remember to position the bag when I get up for a morning nature call, all will be well by the time my alarm clock goes off (too hot in the tent to stay any longer). It doesn't rain in California anymore; and I prefer camping at the alpine fringe, so adequate sunlight should not be an issue. On days that it is, I'll write the next review.

    It could be mechanically possible to affix the bag to the back of my pack, thereby exposing it to sunlight for the hours I hike. I will never do that.

    An extended family all-nights-in-the-same-spot campout looms on the holiday horizon, a perfect opportunity for the initial wet-test.

Field Report

July 22, 2015
   The family campout got rained out, and I never bothered to wet the bag. I have used it subsequently in CA:
    a) 6-day outing in Emigrant Wilderness, 4 camps--varied from hot and sunny to cooler and cloudy with about 2 days of rain.
    b) 4-day outing in Castle Crags Wilderness, 3 camps--really hot and sunny.
    c) 3-day test on the deck--warm, intermittent sun but mostly shady.
    d) 5-day outing in Carson Iceberg Wilderness, 1 camp--hot and sunny half the time, hot and cloudy half the time.
    e) 1-day test on the deck--several hours of direct sun and a day of clouds.

   It was my intention to keep track of the time; and number of hours of sunlight, cloudiness, shade and nightfall for each fill of the bag. That turned out to be unduly onerous, and so confusing as to be useless in a practical sense. My impressions are therefore "generalizations" of circumstances.

    The Emigrant outing I bolted before reading directions. I waited for as long as a day-and-a-half expecting the treatment medium to turn blue. I'm not sure where I got the impression that it should. In the course of this effort I did fill and empty the bag 4 times, an exercise exceeding requirements later read in directions for cleaning the bag in preparation for use. I always run my water through several layers of paint screen. I was impressed that the bag's filter element removed fine algae; and with how quickly water passes through the filter.

    The first fill in Castle Crags was on a ridge line with direct sun exposure for an hour until sunset at 8:30pm; and then again from sunrise at 5:30am until 10am when I emptied the bag. This time I had put in a drop of blue, and the water was a bit lighter at the end but definitely still blue. At the next site I was in trees, but able to keep the bag in direct sunlight most of the time. I started at 3pm. The water did not clear the rest of that day or by 10am the next morning. The third fill I reduced my expectations to being merely a water lugger.

    For the first deck test I did not move the bag around and it spent much of the 3 days in the shade. At the end of the third day, the water was clear. I thought maybe that would kick-start the process and wake up whatever part of it seemed to be asleep.

    The Carson outing seemed ideal for the product--lots of open sky, direct sun, same camp for 5 days. I filled the bag in late afternoon where it got perhaps an hour of bright sun. The next day it was in the sun for a few hours, then mostly in clouds--not certain the balance as I was gone for several hours. On the second morning the water looked clear enough and I drank it. I refilled the bag and added a blue drop about 10am. Again it took until the second morning before the water looked clear. I filled it again right away. The next morning the water still had a slight blue tinge and I poured it on the campfire.

    The vendor was very helpful along the way answering my emails and offering suggestions, including that he would send another bag if Test at beginningI wanted. He suggested a 3-hour test with pictures. The bag was still blue in 3 hours of mostly direct, midday sun; and much less but still slightly blue after 2 more hours under cloudy skies. The vendor felt the bag was sluggish for unknown reasons, but most likely doing its work. After 30 hours (including overnight) the water was clear as the sparkling Hetch Hetchy tap water I put in.

2nd deck test pictures are: 1pm 0 hours; 4pm 3 hours; 6pm 5 hours.

I was prepared to accept the science and believe in the product. If it met the 2-4 hour target, then I would be satisfied. That time frame is not happening; and the degree to which it is not happening has shaken my faith. I knew I would have some trouble with rationalizing when the bag has had sufficient sun exposure. I was delighted to read there is an indicator for when the work is done; and not so delighted to learn the indicator is the blue drop getting clear. I could use the blue drop every time, but it seems now I'm fussing over the concept of putting in a chemical to know when all the chemicals are removed. (I fuss even more over the necessity of packing the teensie little bottle; and might lose sleep Test at 2 hourswondering what could happen if it leaked!) I think if the blue had gone away in the expected time on a few tries, then I might have developed a "feeling" for when the treatment is complete. Now I'm gravitating back to needing the comfort of an action that makes a definite statement--water through a filter or a light going out. Based on the blue drop experience so far, the time would seem to be from mid-afternoon one day until perhaps the sun goes down the next.

    Thirty hours or so is just not often workable in my routine. If I had confidence in 4 hours, that could work--a few hours in the afternoon and an hour in the morning. The water wouldn't be 105 F (40 C) like it gets after a day in the sun and I wouldn't fret over chemicals (BPA-free notwithstanding) leeching from the plastic in all that heat. I wouldn't have concerns about whether there will actually be sufficiently treated water available by the time I get up in the morning.

     I don't know if I could adjust to using the bag exclusively even if it starts behaving as expected. I Test at 5 hourscarried an alternate treatment, which I wound up using most of the time. I might not mind carrying both if the bag had a few modifications. For example, if it were plumbed with a hose outlet and sprinkler, it could make a worthy shower bag. It's already a good water lugger. Perhaps it could have a zip closure that allows removal of the filter medium when not in that use; and then it wouldn't have to have so bulky a cap as now. In fact, if I continue to use the product after the test period, I probably will make those modifications. Then I have 3 reasons to carry the bag, two of which I can know for certain will always be readily available.

Quick shot impressions:
    a) light
    b) inexpensive use
    c) presumably thorough
    d) slow

 Thank you Puralytics and for the opportunity to test this product.  Long Term Report to follow in 2 months.

Read more reviews of Puralytics gear
Read more gear reviews by joe schaffer

Reviews > Water Treatment > Solar > Puralytics SolarBag > Test Report by joe schaffer

Product tested and reviewed in each Formal Test Report has been provided free of charge by the manufacturer to Upon completion of the Test Series the writer is permitted to keep the product. Owner Reviews are based on product owned by the reviewer personally unless otherwise noted.

If you are an avid backpacker, we are always looking for enthusiastic, quality reviewers. Apply here to be a gear tester.

All material on this site is the exclusive property of
BackpackGearTest software copyright David Anderson