This filter (we call it a “micro” filter) uses a 2 liter soft drink bottle, a rubber band a plastic straw, some plumbers putty, and coarse sand and fine sand. The fine sand on the top is .15 mm effective size, and the coarse sand is small pea gravel approximately 2.5 mm effective size. The “baffle” consists of 2 re-used yogurt plastic containers one inside the other with small holes (approximately 1/16 inch in diameter) punched in each. The total cost was under a dollar. This filter has been used to filter water for a vaporizer. The well water here has lots of iron (we assume it is iron, the well is cast iron pipe, and does rust on the outside; and there are constantly accumulating reddish brown stains on the washtub) and sediment that builds up in a vaporizer and ruins the machine in a few weeks of daily use. This filter has been is use for 2 years now. The previous post shows how effective it is in removing particulate matter. If you look closely at the images below you can see the schmutzdecke on top of the sand. This filter has never been cleaned, and still keeps working. We will probably never “clean” it. The flow from it is extremely slow, very very slow – less than 1 cup in an hour. Most people would consider this rate of flow unusable. We are willing to wait for water to flow through the sand. We use the filtered water from it in the vaporizer and there is virtually no build up visible yet after 6 months of use. We have not checked it for biological contaminate removal yet, however we are drinking the water from the well and have been for close to 40 years, and will not hesitate to drink the water from this filter. We do know that there are no pathogens in the well water, but there are likely other microorganisms in the well water because we do not use chlorine and never have. This filter would probably not be practical for any other use. Its pathogen removal capabilities are unknown. Since the cost is under 1 dollar, (actually all of the material we used was “recycled” so, really, our cost was 0, if you had to buy the stuff outright it would probably be about 1 dollar) it would be easier to make a new one if this one stops functioning. Images below:
This is a 2 liter countertop slow sand filter. It filters out iron, and particulate matter from the well water we use here.
This is another view of the small slow sand filter. Notice the “schmutzdecke” on the top of the .15 mm effective size sand.
This is the filter in action. It removes iron, and particulate matter from the well water.
This is a good little set up, but usually well water is normally pretty good, especially compared to city water, as it doesn’t have half as many chemicals in the water, nor is it doused with chlorine. But, if you do not treat your water, this will not remove the bacteria, and something should be done to ensure this is removed from the water.