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  • Remove lid of food grade drum leaving lip to set new lid on. Wash drum, we found Simple Green removed the syrup but it did take several washings. We purchased the drum from Azure Standard. original:P3210002.JPG;;width:640;;height:480
  • Bottom section of pipe being drilled. Pipe is 3/4" schedule 40 PVC with 1/8" holes along the lower part of pipe. original:P3210001.JPG;;width:640;;height:480
  • Assemble pipe in L with cap on lower section and install bulkhead fitting through side of drum. original:P3210003.JPG;;width:640;;height:480
  • Pipe in position in drum, holes are on lower part of bottom pipe. Upper pipe is left a bit long. original:P3210004.JPG;;width:640;;height:480
  • Part of an old truck chassis cut up and welded into a flat base. original:P3210005.JPG;;width:640;;height:480
  • Drum placed on base with pipe in temporary position. original:P3210006.JPG;;width:360;;height:480
  • Pipe held with elastic for now. original:P3210007.JPG;;width:640;;height:480
  • Wash 3/4 cubic foot of 3/8" pea gravel. We got it fairly clean but not perfect. original:P3210008.JPG;;width:640;;height:480
  • Add water to barrel and load in pea gravel, making sure it covers the pipe and is fairly level. original:P3210009.JPG;;width:640;;height:480
  • Mark depth to top of pea gravel. Metal rule is for reference to top of drum. Now add 2 inches (about 1/2 cubic foot) of very fine gravel or course sand. original:P3210010.JPG;;width:360;;height:480
  • Cut and glue pipe into bulkhead fitting. original:P3210011.JPG;;width:640;;height:480
  • Add 500 pounds of fine sand. We used 30 mesh washed beach sand intended for sand blasting. This has fine particles up to about 0.6mm. Keep the sand wet, you don't want trapped air bubbles. It should stop about 2 inches below the hole in the bulkhead fitting. The floating particles fell in, we scooped them out. original:P3210012.JPG;;width:640;;height:480
  • Fill with water and let drain until it stops. Water should now be 2 inches over leveled sand. Add two more inches of water and time outflow. For our test we got 38 seconds for one liter, just about right. original:P3210013.JPG;;width:640;;height:480
  • Add several gallons of strong bleach solution through the outlet fitting. We used 3/4 cup per gallon and put in 5 gallons. original:P3260019.JPG;;width:360;;height:480
  • The hose had been flattened on the roll and it trapped some air giving problems. A nice large round hose is best. You will have to bucket out water as you go or just let it overflow. When done, turn off the valve and let it sit at least a day if not more to sterilize the lower gravel. Open the valve and drain off/discard any excess water. original:P3260020.JPG;;width:360;;height:480
  • Assemble parts for lid. The funnel-shaped fitting near the top is a PVC pipe fitting for 3/4" to 2" pipe. We used thin-wall PVC as we had some in storage. The lid is made from scrap plywood painted with 4 coats of spar urethane. original:P4020022.JPG;;width:640;;height:480
  • Fittings attached, the left fitting goes through the lid and screws into the funnel-shaped fitting. The right hand one is just a cap with a deck screw through the lid and into it. The weather stripping on the edge is to keep mosquitoes out. original:P4020023.JPG;;width:640;;height:480
  • Place the lid on the drum and measure the distance to the water. We had 4" from the inside of the lid. original:P4020024.JPG;;width:640;;height:480
  • Diffuser pipe assembled so top of pipe is about at the water level (4" from lid). The horizontal part of the pipe has 1/8" holes in both sides every inch to send the water gently sideways. Probably not the best design but it seems to work. original:P4020025.JPG;;width:640;;height:480
  • Assembled lid with air vent. Black cloth is screen to keep mosquitoes out. original:P4020026.JPG;;width:640;;height:480
  • Bottom view showing screen stretched over air vent. original:P4020027.JPG;;width:640;;height:480
  • Ready for use with laundry detergent cap over fill opening to keep dirt/bugs out. original:P4020028.JPG;;width:640;;height:480
  • Add ground water (pond/creek) every day for two weeks to a month before using output water for drinking. Leave output valve open at least a little to keep the water about 2" over sand. Every year or two open and clean (see www.biosandfilter.org for more info). Do NOT overclean, it works best when dirty! original:P4020029.JPG;;width:640;;height:480
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