Having enough potable water is always a problem when one is rough camped. I usually take 40L of tap water from home which is used only for drinking and cooking, this lasts a maximum of two weeks, less in warm weather. For showering and hand washing I use river or dam water gathered in the bush.

Sometimes bush water quality, especially of dams, is very poor and turbid and low flow rates increase concern about bugs in the water. Although I only use such water for washing it's hard not to get the odd drop or two in my mouth when showering.

In view of the above and added to the increasing presence of bugs in what may seem to be clean country rivers I decided it was time to improve the quality of the bush water I'm using. To that end I have done some research on water purification and arrived at the following conclusions and solutions.


Objective:
To produce two grades of water; one suitable for washing and another for drinking.

The drinking water should be as close to totally safe as we can make it. The washing water can harbour a few bugs but providing we keep our mouth closed in the shower the risk should be minimal.


The pollutants:
The main issues we have to cope with in bush water are:
Chemicals
Protozoa
Viruses
Bacteria

Let's deal with chemicals first; such things as agricultural run-off from fertilisers and pesticides are the main concern - unfortunately we can't deal with them. There is no practical method of removing dissolved chemicals from water in a camp environment so we must be careful where we source our water. Rivers running through crop farming country are an obvious problem, no way will I take water to treat for drinking from the Murray River in the soft fruit growing area of NW Victoria. However using that water, treated, for showering should be fine.

The other three pollutants we can deal with very effectively by boiling or chemical treatment, indeed the chemical we shall use is identical to that used to make our tap water safe ie. sodium hypochlorite or common household bleach.

I'll not go into the research I undertook to reach the above conclusions but be assured I did due diligence and as I'm going to be drinking the result of what I'm suggesting here then I'll be the first to croak if I'm wrong. Feel free to e-mail me if you would like further information or references.


Drinking water:
The only way to be assured of good drinking water in a bush camp is to boil it.

Whilst sodium hypochlorite will kill most (all?) viruses and bacteria it will not kill two members of the protozoa family in any reasonable time frame or concentration; these are Cryptosporidium and Giardia, parasites which will lodge in the gut and persist for weeks. You do not want to host them!

Boiling, however, will "deactivate" (the scientific term) the little devils and will kill all other viruses and bacteria too.

Water to be boiled for drinking should be, essentially, clear - if it is not then it should be filtered through dense weave material or preferably a sand and charcoal filter until it is - such a filter is easy to make. Boiling muddy or cloudy water runs the risk that organisms may be clinging to particulate matter and may not reach the required temperature to deactivate them.

Clear water should be brought to a rolling boil and sustained there for at least sixty seconds then covered and allowed to cool naturally. A pinch of salt and/or a touch of lemon juice will improve its taste.

At elevations above 500m the boiling time needs to be extended. The highest anyone is likely to camp in Australia is around 1500m at this height water boils at 94C which is still hot enough to kill all bugs you are likely to encounter but as an added safeguard boiling time should be extended to two minutes.


Washing water:
Whilst sodium hypochlorite will not deactivate Cryptosporidium or Giardia it will kill the other viruses and bacteria likely to be present in bush water and given that the protozoas are nowhere near as prolific as the other two organisms the risk of infection from shower water is, I believe, very low.

Again, and for the reason mentioned above, the water to be treated should be as clear as possible. Next, add the required amount of sodium hypochlorite to your container, whoosh it around a bit and leave to stand, covered, for thirty minutes or more. After that time the water should have a slight scent of chlorine, if it doesn't then repeat the treatment. If the chlorine smells stronger than you like leave the water for another thirty minutes and/or decant it across containers a few times - this aerates the water. Again a touch of salt and/or lemon juice will improve its taste.

Although I have described this as a process for producing washing water with the exception of the slight possibility of protozoa it is perfectly safe for drinking and were I away from cattle farming and urban areas I would have no hesitation in drinking it. Indeed this method of water purification is recommended by both the World Health Organisation and the Center for Disease Control.


Sodium hypochlorite quantity required:
It is imperative that the bleach you purchase to purify water contains only sodium hypochlorite and sodium hydroxide. If the label lists any other ingredients reject it. "Own brand" bleaches usually fall into the acceptable category as they are made as cheaply as possible and avoid the additional chemicals to make it "smell nice".

My choice for purification is the product Milton which has been used since about 1915 for cleaning the milk feeding bottles and teats for babies. Milton is simply a low concentration bleach but, for our purpose, its low concentration of sodium hypochlorite makes it easier to accurately measure.

Milton contains 1% sodium hypochlorite, a cheap bleach will usually contain around 5% so if you use the bleach it may be worth watering it down to 1% first? I suggest you go with the Milton, it's cheap enough.

For water purification Milton should be mixed with the water to be purified at a volume of 0.5ml Milton to 1L of water or, a more practical measurement, 5ml Milton to a 10L bucket of water. It is important to use the correct quantity of Milton, never use less and never use greater than, say, 50% more. I use a 5ml syringe to ensure I get it about right, any chemist should be able to supply these for a dollar or two.

As mentioned; over time sodium hypochlorite breaks down into salt and the final amount of it in the purified water should be less than 1ppm. Test strips for testing swimming pools are readily available for checking all is good but, generally, your nose will tell you if the concentration is too high.


Notes:

Ultra Violet:
There is another technique for purifying water which is beginning to become available on the consumer market; Ultra Violet Radiation (UV).

Portable products with battery operation are available and are suited to small quantities of water (1L or so). UV will kill the protozoas in addition to viruses and bacteria but it is very important the water is as clear as possible in order for UV to be effective. Whilst such devices may be very useful in countries with unsafe tap water my feeling is that, at this time, we have insufficient experience of bush use to trust them in that environment.


Use before date:
Sodium hypochlorite has a limited lifespan before it naturally turns to salt. The bottle of Milton I bought yesterday has a use before date 18 months into the future. It is important to ensure the product is replaced at or before that time. I write the date of purchase on mine and will replace it at 12 months.


Bug size:
To give you a sense of the viruses and bacteria we're dealing with:

The bug which is most likely to make us sick is the bacteria Escherichia coli (E.coli) this is found in the gut of most mammals and is usually transferred by faecal to oral contact - animals crap in rivers. E.coli is 0.5 micron long so you would need to place 2,000 of them end-to-end to cover a distance of 1mm.

A technical paper I obtained from North East Water, Victoria, recorded more than 24,000 E.coli in a sample of 100ml of water from the King River in Gippsland.

Viruses can be much smaller, the smallest being around 20nm long so you'd need to place 50,000 of them end-to-end to cover a distance of 1mm.

General bush hygiene:
The single most effective way to promote food and personal hygiene is handwashing with soap and water after going to the toilet and before touching food or food utensils. To this end, I keep a bowl of water on the "kitchen" table and a dispenser of liquid soap, the water is changed and the bowl rinsed out a couple of times each day.

Also, of course, human toilet waste should be buried 100m or more from any water course, including dry ones, at a depth greater than 150mm.

Another good use for Milton is to use it undiluted to clean chopping boards and similar items which may have come into contact with raw meat. The water we use for dish washing is usually about 45C and nowhere near hot enough to kill bugs.

Links:
Milton

Milton Materials Safety Data Sheet

WA government advice on drinking water

USA EPA advice on drinking water

Caution:
I am an electronics engineer and know little of the mysteries of chemistry or micro biology. I offer this information in good faith but it is your responsibility to check its accuracy for yourself.

Last update 11th July 2018