A gravel grid system adds an extra task to the process but is touted as a way to provide a stable surface and minimize ongoing maintenance. Gravel grids (often called permeable pavers) are ...

The purification system is the most intense of the bottles ... The Grayl Geopress is great for backpacking, hiking or camping when clean water may be scarce.

A combination of aeration and rest phases promotes growth of millions of micro-organisms which consume and purify the liquid. The treated liquid is then allowed to settle and any remaining sludge ...