I have a few glass bottles for drinking water. I accidentally left one out of the fridge for a while when it was almost empty. Some algae has grown at the bottom. I don't have a bottle-brush to clean it out with. It's easy to kill the algae with boiling water which should detach most of it, but how do I remove it all of it afterwards?


The hot water removed none of the algae.

4 Answers 4


Use sand.

If you are close to some source of sand, you could put some into the bottle and swirl it around to "scrub" the bottom of the bottle with some hot soapy water. Sand is fine in size, abrasive, and heavy enough to do the job.


If you let some chlorine bleach stand in the bottle overnight any and all organic stuff will have been de-colourised and softened up enough to most likely rinse out.

We soak out water bottles overnight in a basin with dilute bleach every 3 or 4 months or if they have been forgotten in a warm place and of pond slime. We turn them a few times when we walk past and remember so they insides are all cleaned.

Getting old and hard stains out from glass bottles sand is good as mentioned in the other answer. Borrow from aquarium or florist shop if you are too urban for sandpit or building site.

  • 2
    @CJDennis Rinse, rinse, rinse. Gradually, it will lose the odour and taste if the bleach was dilute enough to start. At least you'll know that it has been disinfected.
    – Stan
    Commented Jun 29, 2016 at 0:33
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    @CJDennis If you let the bottle dry out completely after boiling water rinsing there cannot be much chlorine taste or smell remaining. Half of the food you eat has likely passed through bleach treated processing equipment at some point. We use glass and plastic boottles and just rinse once and let drip dry, while the basin smells of bleach faintly while they are soaking the bottles and water never do.
    – KalleMP
    Commented Jun 30, 2016 at 6:27
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    Chlorine bleach breaks down quickly into water and table salt (NaCl). Keep rinsing, and if you want leave the bottles in the sun as light accelerates the breakdown. You can even find instructions online on how to use chlorine bleach to disinfect drinking water yourself so dilution will leave it quite safe, but I think you'll have no trouble washing it out.
    – briantist
    Commented Jun 30, 2016 at 12:27
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    @CJDennis Do you taste detergent on you glass after washing and rinsing?
    – paparazzo
    Commented Aug 13, 2016 at 10:22
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    Caustic soda is my go to for this sort of thing. Like cleaning the bottom of a red wine decanter. Tasteless, harmless (once rinsed out), its what 99% of your dishwasher powder is. Or use dishwasher powder if that's what you've got.
    – TomC
    Commented Aug 20, 2018 at 3:59

Denture cleaning tablets are useful for cleaning out bottles with a neck too small to admit a brush or hand.


Vinegar + Baking Soda + Magnet Scrubbers(for hard to reach places)

Example Scrubber(Randomly selected from Amazon), so you get the idea. Also good for Fish tanks

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