We were in the middle of planning a 3-month trekking trip to Chile, Argentina and Bolivia. As we intended to spend up to 10 days at a time away from "safe" drinking water (in other words bottled water), purifying water was one of our concerns prior to departure. We knew for a fact that mainly human and / or animal faeces would contaminate most of the water sources. The other difficulty we were to meet was ice-cold glacier water rich in sediment.

A safe way to prepare drinking water is to boil it before use. But boiling all our drinking water was not really possible for two reasons. The hiking we intended to do was strenuous (up to 12 hours a day). As we didn´t use porters or pack animals at any stage, carrying the extra fuel needed simply was not a tempting idea. The other concern was altitude. At high altitude you have to drink a lot (up to 5 liters per day), especially when doing physical activities. As it takes longer to boil water at high altitude, this again would have demanded extra fuel - and time.

 

Chlorine could have been a choice, but eventually we decided against it. The reason for that was the fact that chlorine needs prolonged contact time (=over night treatment) to disinfect properly, when the water to be treated is ice cold (as the case often was for us). Organic debris mud, sediment etc) also interferes with the action of chlorine, which meant that the water preferably should be filtered anyway prior to treatment. As our trips usually last several months a year, the continuous use of iodine as a disinfectant could affect thyroid function. This left us with the choice between different ceramic filters. Earlier we had seen some (slow) hand pumped versions and heard the complaints from the frustrated users. As we knew we would need at least 3 liters of water per person per day, we needed something easier and faster.

 

At the Helsinki hospital for exotic diseases, we received not only the required vaccinations, but also an excellent piece of advise. This was the first time we heard of Nerox water filters, used worldwide by humanitarian organizations. When we contacted Mr Kari Aalto at Nerox just before Christmas, we were informed that the filters usually were sold only in large quantities. To our luck, in true Christmas spirit, we were offered to bring a filter with us to test it out.

 

The following comments about the Nerox filter are based on extensive use during two separate trips (1997 and 1998, both of 3 months duration) to Argentina, Bolivia, Chile, Ecuador and Peru. Seldom we bought bottled water at all. When in urban areas, we purified municipal water instead. 

 

Our main water source were streams or rivers. We found the multipurpose U bag very handy to fetch water in. At rare occasions a cooking pot was needed to fill the bag, when the water level was extremely low in the stream. Finding a suitable location to achieve a difference in height never was a problem. Often the U bag ended up in a tree or on a stone, with the clean water bag below. The unit was easy and fast to assemble - and this is important when you are hungry and tired! In general the filter prepared enough water for the evening while we put up the tent. After dinner we often filled up the U bag and left the filter system running during the night. In this way we always had the next day´s drinking water ready when waking up in the morning. 

 

When filtering relatively clean water, the procedure was very fast. During our extensive use, we didn´t see any decreased function in the filtering speed other than with heavily sedimented water. The bluegray glacier water caused the filter to clog up, and slowed down the filtering procedure. Cleaning out the sediment from the filter once or twice during the cleaning process easily solved this. Cleaning the filter was straightforward also when out in the wilderness. The only drawback was cold hands… Even water with high turbidity cleared up and tasted fine. When drinking such large amounts of water daily, the lack of chemical taste was an additional benefit.

 

Whenever we could, the whole set was rinsed with clean water. Usually though, the filter had to be cleaned with the same contaminated water that was to be filtered - this especially concerns the clogging up with glacier water. The possibilities to dry things out were poor and the clothes, sleeping bags and tent were often damp, when we set off in the morning. Also the filter unit had to be stuffed into the backpack while wet. A proper hygienic level was difficult to maintain in general, and therefore a risk of cross contamination during handling of the equipment was obvious. The tube that brought the safe water into the clean bag also slipped out of place a couple of times and fell onto the ground. To prevent this, there is a small plastic piece to hold the tube in position, but to save weight, we had left it at home.

 

A routinely disinfection of the clean part of the system would have been appropriate, although we did not practice it. We still evaluated this risk small compared to the handling of food with dirty hands.

 

Fellow travellers and hikers were sometimes suspicious in the beginning, but more often than not, we ended up supplying other teams with clean water. Green with envy, they gave up their own frantic pumping by the riverside, and enjoyed the effortless principle of gravity. The real advantage with Nerox is its ability to purify water for a large group of people, and that it all happens while you are busy with establishing camp, preparing food and so on. Periodically the filter supplied up to 6 persons with the daily need of safe water. The system is perfect for expeditions and base camp use.

  

Nerox Professional

The Nerox filter is difficult to beat when it comes to efficiency and easy filtration. We have been extremely satisfied with the product. For a single person, it is too heavy to carry in the backpack, but for a group the advantage is obvious. As mentioned before, it is difficult to assess safety when out there using the filter. We have used the filter in cities, on the countryside, in the mountains, on glaciers and in the jungle. We have taken water strait from the tap, from ditches, rivers and lakes. The filtered water has always been clear and tasteless. So far so good.

 

Our first filter system got destroyed in Bolivia, when trying to save a pet monkey with a gastric dilatation. Johanna, who is a veterinarian, needed a tube for letting the trapped gas out of the stomach, and so the Nerox tube was sacrificed. Unfortunately the monkey was in too bad state to be saved. 

 

A new filter will definitely be in the backpack again for the next trip!

 

Johanna Miemois and Patrik Johanson

Yrjönkatu 1 C 25

00120 Helsinki