There are four basic elements to a gravity water system: source, intake, sediment removal, and storage. Of course, you may have to deal with some troubleshooting down the road as well.Source
The source can be any supply of free water. Spring, creeks, lakes, rivers or even collected rainwater are all viable sources. However, each has advantages and disadvantages to a homeowner. For instance, if you use flowing water, will a flood or mudslide possibly destroy your intake? First on your to-do list is to identify all water sources available to you. Even swampy areas can be a source, so do not be afraid to list everything. The next step is to have the water tested at the county from each source for pollutants.