Need to urgently remove algae from large plastic container

[StripeyKnickersSpottySocks]

I didn't fully empty the water container in the camper van and there's some green algae in the bottom. I can't reach it to scrub.

I've put boiling water and bicarb of soda in but it doesn;t seem to be shifting. What else can I try? We use it for drinking water so guess that bleach would be no good?

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Can you put rice in with some water and give it a good shake? I think that's a tip for cleaning vases, but it might work.

Not very environmentally friendly, but what about bleach? It would kill anything nasty - you'd obviously have to rinse through a lot.

Try using those drops you use for washing veggies and fruit (don't know what they're called in the UK but they must exist over there!!). Just squirt the lot in and leave - it's chlorine-based so afterwards the container will be safe to use but might smell a bit of swimming pool!

Something like this

Would something like Milton do the trick?

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Bleach will likely work and it's not going to be harmful so long as you rinse the container thoroughly. Bleach is chlorine which is already put in our drinking water to sanitize it, meaning to kill bacteria, algae, fungi, molds, etc. But by the time the water comes through our tap, the bleach solution is extremely weak because it's highly diluted by the water.

You might want to start by trying a 1 part bleach to 10 parts water solution and letting it sit in the container overnight. That's the ratio a friend taught me to use decades ago to get the stink out of kitchen sponges, which is caused by not thoroughly wringing them out when you're done using them, and that attracts bacteria.

If that relatively weak solution doesn't work, try a stronger one. I doubt you'd have to go all the way up to straight bleach, but I don't know for sure.

If you can lift the container, it might be good to shake it around with the bleach solution inside it. Also, do you have or can you purchase any sort of long-handled brush you can use to scrub the inside while the bleach solution is in there? Or do you have something like marbles or decorative glass stones or even river rocks or smaller pebbles — anything that's relatively heavy for its size and has rounded edges? If you are able to pick up the container and shake it around while it's holding the bleach solution, adding something like the objects I've just mentioned could help scrape the algae off the inside without damaging it. This might not be necessary if it's only a thin layer of algae but it couldn't hurt as long as you don't use anything with sharp edges that could scratch the plastic. Good luck!

Undiluted bleach is extremely caustic and can burn your skin, but its one and only ingredient (unless you buy some specialized product with additional ingredients) is chlorine, which is the same substance put in your drinking water to disinfect it, i.e., to kill bacteria, algae, fungi, molds, etc. Anyone who gets their water from a municipal water treatment plant is drinking chlorine every day, but it's in a solution with water where the proportion of water is magnitudes higher than the proportion of chlorine.

I just looked it up and the current EPA drinking water standard for chlorine is a limit of 4 parts per million. In case you can't imagine what that means, let's say you have 4 ounces (= ½ cup) of chlorine bleach. Now combine it with 1 million ounces of water. I hope that illustrates how dilute the solution is.

I learned a long time ago from a friend that bleach is not bad for the environment unless you're pouring a crazy amount of it down the drain because it will be diluted by exceedingly large quantities of water. However, that doesn't mean you should use bleach with abandon. For example, don't pour it on the ground, or assume you don't need to wear gloves if you're going to be scrubbing something using it because it can still harm your skin at a standard disinfectant solution of 1 part bleach to 10 parts water.

And, of course, don't think this means you can ever drink bleach. NO! You'd have to mix it with a million parts water to make it safe! No one has a cocktail shaker that big 🤣