Make sure to boil your water if you get it naturally from streams, lakes or ponds. Invisibles like cryptosporidium and Giardia Lamblia are common, and it can be a big mistake if you don't watch what you're drinking! They generally won't kill you, but are definitely something that would feel like they were. If you are at a higher elevation you'll want to boil the water longer than normal. But even though boiling is good, it doesn't get rid of mud or chemicals in the water, if any.
Try using water filters to make your water clear and healthy. Sometimes you don't have to boil your water if you use a filter, as they rid of most bacteria and chemicals too. However they don't get rid of viruses, seeing as they are too small for the filter to catch.
You can also use a chemical solution like chlorine to rid of bacteria and viruses, but do not affect chemicals, sediment and sometimes not all protozoa. Iodine is similar, but may offer limited protection against cryptosporidium. Just add a few drops of the solution, shake it well and let it sit for a few minutes.
