It's not a question of if you'll get sick, it's a question of when, how often and how badly. This place seems loaded with evil bacteria just waiting to get into our intestines. There's no avoiding it and there's no getting used to it. In many developing countries, travelers and expats might have a few bouts of what is often called travelers diarrhea (or Moctezuma's Revenge, Delhi Belly, Thai-dal Wave, etc.) but eventually develop an immunity after repeated exposure to bacteria that their system is not used to. There is no immunity to what's in the water here; even Afghans get afghani-sickness.
The basic symptoms of Afghani-sickness are varied because it can be caused by many different things. Abdominal cramping, fatigue, diarrhea, vomiting, nausea, dizziness, bloating, weight loss, infections of the eyes or ears, headaches, fever, body aches . . . any combination of the symptoms.
Some of causes. Afghanistan is plagued with many, many parasitic diseases. If it exists, we probably have it here. Various worms, amoeba, and other fun things like giardia, cholera, e. coli, salmonella, hepatitis are considered "wide spread" in the country. 90% of the water is contaminated due to the non-existent sewage system. Yep, that's right, our water has human and animal waste in it. According to the World Health Organization, Afghanistan's water supply and sanitation are among the lowest in the world (along with several sub-saharan African countries and countries in Southeastern Asia). About 13% of the population has easy access to water (19% in Urban areas, 11% in rural) and only 12% has access to sanitary water (25% urban, 8% rural). The situation can be very depressing.
Now we'll look at prevention. We only drink purified water. We brush our teeth with purified water. All produce we eat goes through an "iodine bath." We soak it in an iodine/water solution for 20 minutes and then rinse it with filtered water. This kills off nasty little things like Hepatitis A and amoebas. All meat must be bought from a reputable source and then washed, cleaned and thoroughly cooked. Milk and yogurt needs to be carefully bought and carefully stored. We buy "Milk-Paks" which are boxes of milk that don't need to be refrigerated until opening. I never open my mouth in the shower and wash my hands religiously throughout the day.
But even with these methods of prevention, sickness will still happen. Our housemate was sick for a month after eating rice from a plate with contaminated meat (she's a vegetarian). Other forms of contracting Afghani-sickness include breathing in contaminated dust, eating after washing your hands and not completely drying them, eating nan (bread) that was sprayed with water to maintain freshness, or sharing a plate of food with someone who hasn't washed their hands with no cutlery (have we mentioned Afghans don't use silverware?).
There are little sicknesses here and there. Unfortunately these days happen often enough that most people continue life as usual within proximity to a bathroom. I've been lucky to have only one seriously sick day (24 hour death virus, I was sure I was on the next med-evac to Dubai but woke up the next day alive, exhausted, but better). I know I will have more and dread their arrival.
Some final words. As I mentioned above, Afghans never get used to all the bacteria and parasites in their country. How awful to think that it could even be possible to get used to drinking fecal matter. The life expectancy for Afghans is around 42 years old. 1 in 4 children die under the age of 5. Although issues like continual war, drought, famine, disease, etc. can all be pointed to for these dismal statistics, the fact is that a lot of Afghanistan's problems have to do with the lack of sanitary water and education on hygiene and contamination prevention. A lot of NGO's focus primarily on water supply, purification and retainment. In many ways they are fighting a losing battle against time and lack of funding. A lot of promises that were made to Afghanistan concerning reconstruction have been forgotten or diverted to other locations.