Saturday, August 02, 2008

The $10 water filter

One of the most annoying things about living in Malaysia (as compared to Singapore or Australia) is that clean water does not come out of the tap. It's not drinkable, the colour's slightly off and if you leave it to settle for a while you can see sediment in the bottom. The kitchen tap has a water filter attachment to it, but I don't think it's been changed for a while so the water trickles q-u-i-t-e slowly. Rather than blow $50 - $200 on a filter that will last for up to six months, I took a cue from a couple of sites (see here and here) and cobbled one together for about $10. After a month of use, I'm happy to say that this filter removes all visible sediment from Malaysian tap water. =D

Interested? Here's what you need:
1. A large bottle that will be the chassis of the filter. It should have a narrow neck with a large body that can rest on top of your water collection jug of choice - I bought a 4-litre bottle of water, used the contents and recycled the bottle. It was the last bottle of water I ever bought!

Equal proportions (by volume) of sand and gravel. This is where the real filtration power lies. I also like to use different degrees of coarseness for both, so I have four layers of fine sand, coarse sand, small pieces of gravel and large pieces of gravel. Remember that the thicker the layers are, and the more layers you have, the more effective the filter is going to be. Where to get sand and gravel? They are literally lying around everywhere - I picked mine off from pits just outside my school. (You could also go to the beach - and it costs nothing!)

Cotton puffs

Coffee filter papers (entirely optional, see below)

Large pail and distilled white vinegar for disinfecting everything.

Once you manage to scrounge up everything in the parts list, it's time to assemble:
STEP 1: DISINFECT AND CLEAN EVERYTHING THOROUGHLY. Does the idea of relying on sand and gravel that you've picked out from the outside to give you clean water make you queasy? Me too, which is why the first step is to disinfect everything in a bath of water mixed with a little vinegar. The sand and gravel especially were soaked in disinfectant, then rinsed three times before thoroughly dried in the sun. DON'T SKIP THIS STEP.

STEP 2: PREPARE THE BOTTLE by drilling a small hole in the cap (that's where the water comes out) and cutting a large hole in the bottom (that's where water comes in - be careful of jagged edges and cover them with waterproof tape if they become a safety hazard). Disinfect these too.

Make sure the cap is securely screwed on and place the bottle - cap side down - onto the jug of your choice. Start with a opened coffee filter filled with cotton puffs into the neck of the filter. Wet the puffs and aim to create a level layer. Layer the sand and gravel with the finer grains on the bottom, followed by the coarser grains of sand, and then the small gravel pieces followed by the larger gravel pieces. I separated each layer of sand and gravel with a layer of coffee filters - I did this with the mind that I would one day have to change the sand, so the coffee filters would make my job easier.

STEP 4: FLUSH, TWICE. It's almost ready! Run the filter through two loads of water first to help the sediment settle and flush out any remaining undesirable elements. Only after that are you ready to use your nifty new filter.

REMEMBER: This filter only removes visible sediment from tap water, and not microbial elements. In the end, I still always boil the water that comes through the filter before drinking!


AddThis Social Bookmark Button

1 comment:

Celine said...

Very green! Me likey! :)