1. How to make a good water filter

2. End Product
Dirty water in
Clean water out

3. 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

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

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

6. 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
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Small amount
of these

7. 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

8. 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 !!!

10. 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 !

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

12. 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

13. 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

14. 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 !

15. 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

16. 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