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Possible Uses for Used / Spent Water Filter Carbon

Other Things You Can Do with Spent / Used Water Filter Carbon

Used water filter carbon has a great “after life”. It can be reincarnated for several uses including fighting bad smells, mould and composting.

First give the used carbon grains or “carbon block” (ie compressed carbon) a rinse in cold water. Then dry it thoroughly, ideally in the open air (fresh air seems to recharge it better than air inside a room).

Fighting Smells / Bad Odours.

Put the dried carbon in a sock or stocking and leave it in required places like the fridge, the loo, as a car air freshener or a drawer freshener. Even your old trainers! Or your pets bed. It will absorb the smell.

Every few months, as it wears out, repeat the rinsing / drying process (see above).

Fighting mould (eg in bathrooms).

As above put it in a stocking and leave it in the area where the mould is growing.


When the used carbon really does seem finished off ie you’ve been through a few cycles and it’s not fighting the mould or smells quite as well it will still be great for composting. (But check the Warning below about Composting Old Carbon)

If it’s in compressed “carbon block” form, like one of our USC2000 filters, crush it up and mix it into compost or soil - it also works very well in pot plants.

The carbon won’t just sit in the soil passively but will positively add to it by increasing aeration, and water retention.

Warning about Composting Old Carbon

If you’re using a reverse osmosis water filter it might be because your water has particular poisons in it such as heavy metals - like lead or arsenic.

The carbon will have trapped and concentrated various contaminants. Most of these will be organic which will easily break down in the compost. But lead and heavy metals won't.

So don't compost old carbon if you think there's a risk of heavy metals getting into the compost becuase this will end up in the plants you're growing. And guess who's at the top of the food chain...

These aren't in normal UK mains water. But if you're on a private water supply or think you might have old lead pipes in your house then play it safe.

Can you actually re-use / regenerate old carbon? Checkout this information

Go back to Main page about recycling water filters

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