3Material needed One large vessel, at least 32 inches tall This will be the biological filterOne small bucketThis will be the water supplying sourceOne plastic pipeStones of various sizes (see slides)Material to make things water-tight
4Schematics of the water filter Water reservoir (withdirty water)Water fit for drinkingSlow sand water filter
5Step 1: Prepare vessel Vessel must be at least 32 inches tall Make a hole at (about) 12 inches from the top
6Step 2: Find sand/stones for the filter Buy/find stones/sand of various sizesYou will need a lot of very fine sand (check Home Depot !)Small amountof theseSmall amountof theseA lotof theseSmall amountof theseSmall amountof these
7Step 3: Wash sand and stones It does not matter if the water is not clean, just wash them to get rid of mud that will clog the filter
8Step 4: Fix the draining pipe Use a longer pipe if you have a taller vessel – the taller the vessel the better the filterMake sure the pipe reaches to the bottomMake sure the hole does not leak !!!
10Step 5: Add sand The filter is ready ! Finally, put in the sand Left 5 inch space between the sand and the hole (where the pipe is protruding)The 5 inch space is used to maintain water level for the beneficial bacteria which are aquatic !The filter is ready !
11Step 6: Make water reservior Use (another) small vessel (bucket) as water reservoir to supply dirty water to filterHole
12Step 7: Finishing up…Fasten the water reservoir on top of the filter vesselIt is important that the sand inside the filter vessel not be disturbed after the filter is in production
13How to use the water filter You need to run the filter for 3 weeks before drinking the waterThe beneficial microbes need 3 weeks to multiply and for a layer on the sandThe microbes live on the top 2 inches of sand
14Maintaining the filter After prolonged usage, the efficiency of the filter will decrease (the output flow will slow down)Remove 2 inches of sand from the top, wash it and put it backLet the filter run 3 weeks before using the water for drinking !
15Final adviceMake 2 filters – in case you need to wash the sand of one of the filter, you can use the other oneHave separate containers to store dirty and clean water – never use a container that held dirty water to store clean waterMake a pre-filter to filter the dirty before feeding the water to the biological filter
16How to make a pre-filter Use a 2 liter coke bottleCut the bottom outTurn it upside downProp the spout with 5 or 6 cotton ballsFill the coke bottle with fine sandPre-filter is now ready for use – pour dirty water from topWash the sand occasionally and replace cotton