Sand and charcoal pre-filter

Think of this as a helper for your real filter, not a must-have.

Layers of gravel, sand and charcoal catch silt and improve taste, so your real filter lasts longer.

This doesn't make water safe to drink on its own. Always boil, bleach or run it through a proper filter after.

Rinse the sand and gravel well before building, and replace the charcoal every few weeks of use.

Steps

Cut the bottom off a 2 L bottle and turn it upside down. Put a cloth in the neck.
Layer crushed activated charcoal, then fine sand, then coarse sand, then gravel.
Pour water in slowly and throw out the first few litres.
Always boil or bleach the water after.

Activated charcoal (granular)

Improves taste and smell.

Filter sand

Washed sand for the middle layer.

Pea gravel

Bottom layer to stop sand washing out.

Food-grade bucket

Makes the filter body.

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