There are several other methods including: laying potential drinking water in plastic bottles in the sun all day. The goal is to use the ultraviolet rays of the sun to kill any bacteria in the water. Plastic is chosen because it is less opaque to ultraviolet than is glass. However, this way does not remove salt, chemicals or trash from the water.
Reverse osmosis is available commercially also. It seems to do a good job, however, it is more expensive, and requires that you purchase the equipment and replacement filters from time to time as needed. It removes salt and some chemicals, along with trash.
Big trash should be filtered out by running the supply water through a cloth before processing with any method.
There are some small units available on the market that just use filters. However, they do not remove chemicals, or trash from the water. They seem to be ok too, but again you must purchase these.
Whereas the items below can be home made. Or set up in an emergency.
I do not know of the effectiveness of any of the methods listed here, as it somewhat depends on the skill of the persons who make them. Thus, I furnish no guarantees what-so-ever. Thus, the water from any homemade system should be tested.
Distillation removes most of these bad items. The first method shown here uses a “column still” like the ones commonly used in the petroleum industry. The purpose of the column is to produce a low pressure zone above the input water at the top of the column. Water boils at a much lower temperature in low pressure. Thus, you can actually distill water at room temperature.
However, petroleum products are often more volatile than water, so they may appear in the output. Most chemicals and trash, including salt from seawater are removed.
Thus, you should consider your water source before choosing a method.
It is believed that low pressure, room temperature distillation kills bacteria just like boiling, and common high pressure distillation, but you should have the output tested before drinking.
Note: the still has two parts (below) in it's description, whereas the 2nd method needs only one.
The 2nd method discussed here actually boils water at higher pressure and temperature. The goal is to conserve energy in the process. However, again, chemicals and trash are not removed.
I hope these can be helpful in a world so badly in need of fresh drinking water.
Distilling Seawater at Room Temperature Part 1
Distilling Seawater at Room Temperature Part 2
Boiling Large Quantities of Drinking Water
in an Emergency
Easy Explanation in Poetry
by John N. Hait