How to make a good water filter http://webarchive.cms-uk.org/water/concept.htm

End Product Dirty water in Clean water out

Material needed One large vessel, at least 32 inches tall This will be the biological filter One small bucket This will be the water supplying source One plastic pipe Stones of various sizes (see slides) Material to make things water-tight

Schematics of the water filter Water reservoir (with dirty water) Water fit for drinking Slow sand water filter

Step 1: Prepare vessel Vessel must be at least 32 inches tall Make a hole at (about) 12 inches from the top

Step 2: Find sand/stones for the filter Buy/find stones/sand of various sizes You will need a lot of very fine sand (check Home Depot !) Small amount of these Small amount of these A lot of these Small amount of these Small amount of these

Step 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

Step 4: Fix the draining pipe Use a longer pipe if you have a taller vessel – the taller the vessel the better the filter Make sure the pipe reaches to the bottom Make sure the hole does not leak !!!

Step 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 !

Step 6: Make water reservior Use (another) small vessel (bucket) as water reservoir to supply dirty water to filter Hole

Step 7: Finishing up… Fasten the water reservoir on top of the filter vessel It is important that the sand inside the filter vessel not be disturbed after the filter is in production

How to use the water filter You need to run the filter for 3 weeks before drinking the water The beneficial microbes need 3 weeks to multiply and for a layer on the sand The microbes live on the top 2 inches of sand

Maintaining 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 back Let the filter run 3 weeks before using the water for drinking !

Final advice Make 2 filters – in case you need to wash the sand of one of the filter, you can use the other one Have separate containers to store dirty and clean water – never use a container that held dirty water to store clean water Make a pre-filter to filter the dirty before feeding the water to the biological filter

How to make a pre-filter Use a 2 liter coke bottle Cut the bottom out Turn it upside down Prop the spout with 5 or 6 cotton balls Fill the coke bottle with fine sand Pre-filter is now ready for use – pour dirty water from top Wash the sand occasionally and replace cotton