A few drops of bleach will purify a gallon of water and can be had for a fraction of a cent. There are various other chemicals a person can add, as well as various machines to purify water, as well as various ways to heat the water (stovetops and solar panels come to mind, but there may not be enough fuel for stovetops and solar panels may still be unaffordable). Some of them like bleach are very affordable. So why is impure drinking water still such a problem globally when bleach is so effective and easy to use? Is it lack of education on germ theory, lack of motivation on the part of the drinkers, lack of access to bleach or what exactly?
http://www.iht.com/articles/2005/08/19/news/RSWATAFRI.php
Chlorination…is often resisted because of the taste, color and smell of the treated water
Ah. Good article though. They covered putting water in clear plastic vials and setting them on pieces of tin for 48 hours to kill off all the microbes with UV light.
I think much more important factors are that people either have no money to pay for bleach (when trying to live on less than $1 per day, expensive imported chemicals are unlikely to be high on your list), or are totally uneducated in basic hygenie.
One life-saving measure that is frequently mentioned is getting people to wash their hands. The obtacle is not so much the availability of soap (even cheaper than bleach) but just telling people about the concept and persuading them to do it.
Bleach is dirt cheap at around 30-40 cents a gallon when bought wholesale. A gallon of bleach will purify about 2000-4000 gallons of water.
I think homemade filters are feasable like the one described there. Just use dirt/sand and some kind of cloth.
I would think it has to mostly do with money. Even if bleach is cheap when bought wholesale I can’t imagine that a lot of people would want to put it in their water, due to taste factors. As well, cheapness is relative. The other major obstacle, IMO, would be education about the benefits of clean water. In a lot of poor areas around the world people use the same water source for everything, toilets, laundry and drinking. You would need to educate these people to not do this, as well as provide a way for them to clean and drink. I would imagine this would be very expensive.
As well, plain old human laziness has a lot to do with it. A few years ago there was a major problem with the drinking water in a little town called Walkerton in Ontario. 7 people died, and hundreds became sick. The problem was that the people in charge of the water purification plant were to lazy to properly check the water supply.
IMHO: Developed countries don’t care enough to pay for safe drinking water supplies. I suggest reading Paul O’Neil’s The Price of Loyalty, which explains how scandalously cheap it would be to do so.
Are there health implications for using bleach-purified water as a constant source, rather than just on occasions? Including for babies, ill people, etc?
There are many contaminants in water that are not removed by disinfection. In Bangladesh and West Bengal, India, for example, the groundwater is contaminated with naturally occuring arsenic. Millions of people are slowly being poisoned by drinking this water:
Arsenic is an element that is not removed by disinfection or boiling.
Other contaminants include those found in petroleum wastes and other hazardous wastes, such as PCBs. Water can also be contaminated with heavy metals, including lead, mercury, chromium, or cadmium. Disinfection and boiling don’t remove these contaminants. In the case of volatile compounds, such as those found in gasoline, even distillation does not remove them. The vapors carry over with the water.
Not entirely true. Distillation is in fact the best method for separation of organic compounds and organic/water mixtures. Distallation is how all the components of crude oil are separated. As far as water is concerned, distillation would be a highly effective method provided there is adequate boiling point differences between the substances to be separated. The exceptions are those mixtures (e.g., ethyl alcohol-water, and ethyl alcohol-benzene-water) that form constant boiling azeotropes.
Absolutely true. However, by far the largest problem with drinking water is contamination with excrement (animal or human) or parasites such as bilharzia, guineaworm, etc.
These all lead to infection and sickness by the action of various organisms which can be killed with bleach, UV light, boiling, etc. or removed by some type of microfiltration.
Adding bleach to drinking water is indeed trivial by first-world standards. However, so is vaccination, rehydration therapy, keeping human shit away from the water supply, and any number of other things which simply do not happen in the third world. Getting the money, basic education and logistics to coincide for any of these things is non-trivial.
For example, getting bleach in the west is easy. In africa, manufacturing it is often beyond the reach of local industry, so you have to import it from somewhere far away and get it to where it is needed, despite the difficulties of rotten ports, roads, customs systems, etc. Then you have to persuade probably illiterate and uneducated subsistence farmers to let you put this funny-smelling chemical in the water they have collected. You have to educate them that they should never drink anything other than the treated water, and that they should use the treated water whenever they wash themselves, their utensils, their food, etc. or whenever they prepare food. You then have to keep this going 100% of the time for the foreseeable future. If ever you run out of bleach, or someone forgets to dose the days water supply, or brews a batch of beer with untreated water, or people swim in the river, you risk a disease outbreak.
Bleach is one tool that can be used to cut the disease burden - however it won’t solve the problem, and one of the key enablers needed for it to work (education) will probably also help reduce the problem even if no bleach is available. If everyone in the third world knew what cased sickness, the battle would be nearly won.
You got the same answers when you asked this exact same question last year. Nothing’s changed since then.
True enough, if your distillation apparatus is set up to separate the fractions. In many distallation setups, however, such as those used to produce fresh water from seawater, the entire vapor fraction is carried over and condensed. Soluble solid contaminants, such as dissolved salts and metals, are left behind, but volatile contaminants are carried over with the water vapor and not necessarily removed.
You didn’t contribute anything to that thread either. So yeah, nothing has changed.
Well, my post in that thread apparently killed it, so perhaps I can repeat the favor here.
Well yes, but since you are using seawater desalination as your example, typically there would be little or no volatile organic contamination to have to worry about!
Speaking of organic contaminents
Depending of course what the source of your seawater is. I can think of a few harbors that would have plenty of VOCs in them!
In any event, upon rereading the thread, I have to take issue with your original assertion that distillation would be a highly effective method to separate organic/water mixtures. The maximum permissible levels for most VOCs in drinking water is measured in parts per billion (ppb). Trying to separate VOCs to achieve such low concentrations via distillation is not really practical. It would be much more feasible to utilize air stripping (for large scale water treatment) followed by activated carbon filtration.
Most drinking water related deaths aren’t obviously related to drinking water. They are categorized as just another illness that you either get over or die from. Even if it is traced to water, 99% of people drink that water every day without incident. It’s just not all that high up on the “things that can kill me” list. There are much more pressing and obviously life-threatening things to worry about.
Anyway, the biggest problem with water is not simple contamination- every culture has developed a method of heating or fermenting that minimizes that. The biggest problem is access to water in general. Water is increasingly privately and tightly controlled and sustenance farmers who have been farming for endless generations are finding their sources appropriated. If you want to learn more about this subject, a good place to start is Arundhati Roy’s fascinating essay The Greater Common Good.
Other worrying factors involve heavy metal poisoning of major rivers and irreplaceable water sources. When you look at the sheer amount of damage these things can cause, a few deaths to dysentery pale in comparison.
Neither one of us, in truth, has really addressed the OP so first of all let’s agree to agree on that. Secondly, we are not and have never addressed issues such as the feasibility or cost or anything else similarly related in regards to the technologies being discussed. I simply made a point, which I will stick to on a theoretical level, that distilation can be an effective method of separating organic constituents from one another and from a water/organic mixture and that the degree and success of that separation is based on the boiling point difference of the substances being evaluated unless they form a constant boiling azeotrope. I never addressed the issue of whether or not air stripping would be an effective means because, frankly, the subject never came up!! You want to discuss the merits and effectiveness of distillation versus air stripping then that’s a completely different topic for discussion.
Fair enough. For what it’s worth, when I first made the comment about distillation, I was thinking of the desalination plants on submarines. It’s drilled into submariners’ heads that such plants do not remove volatile organics. For this reason, you’d never want to start up the plant at the pier, or anywhere near shore, for that matter.