When the power goes out so does the water pressure. Gravity feed water filters will allow you to safely purify surface water for drinking from creeks, rivers, ponds and swimming pools. No pressure or plumbing connections needed. The perfect Y2K household water solution. These filter units remove disease-causing bacterial microorganisms and chemicals out of water.
Viruses are another issue.
In general, viruses do not exist by themselves in water. They are usually found in clusters around organic material. These filters remove organic material. The ceramic filters in these units are impregnated with particles of silver to prevent bacteria growth inside the filter. Gravity Feed Water Filters CWR makes a stainless steel water filter units that come in either a two or a four-filter configuration.