Jim
Explanations about constructing homemade slow sand filters are on numerous web sites and have been for years. Typically, they use 5 gallon buckets with layers of sand (sometimes they specify the size of the grains of sand), gravel and charcoal. A little bit of research will show how to construct one to experiment with and to maintain for use in an emergency. Typically these are not very effective against water that is contaminated by chemicals. While barrels will allow you to filter more water, you will not be able to move it and there will be the problem of bringing enough water to fill the barrel in the first place. Five gallon buckets of water will weigh about 40 lbs and that is a safe amount of weight for most adults to carry. Alan W. in Maryland
James,
For slow sand filter designs, see the OasisDesign.net web site.
The critical point is that the surface of the sand supports a film of slime that does the heavy lifting of the filtration. Disturb the film and you degrade the filter. Pouring 5 gallons of water into the filter from a height of 3 feet will degrade the film, so you need a way to drip the water in. Also, keep in mind that the slime is a biologically living film of bacteria. It takes some time to develop and will starve if it is not fed (used). Regards, – J.H.
Jim and Family:
See the Wikipedia page on slow sand filters. I used to work in an office that shared space with a water treatment engineer. They talked about using 60 foot deep sand pits to filter water for an entire town. The more sand it goes through, the cleaner the water coming out from the bottom is. It scales up nicely, and its very cheap to setup. Best, -InyoKern