How long can a human go without peeing? © iStock

How long can a human go without peeing?

When nature calls, it's generally a good idea to obey when convenient, but by knowing your bladder means you could go longer than you think without a wee.

The bladder holds 400-600ml of urine. Normal urine production is around 1.5 litres every 24 hours, so that would give you nine or 10 hours to completely fill up.


However, you can drop to as little as 400ml of urine production a day for short periods without suffering harmful consequences. This could conceivably give you as long as 36 hours between trips to the loo.

Asked by Ben Warwick, Poole

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What happens to toilet paper when you flush it?

Getty © What happens to toilet paper?
© Getty Images

Toilet paper is made from short cellulose fibres, which is why it tears so easily. In water, those fibres quickly come untangled and form a thin sludge that’s easily carried by the water flow in the sewage system. By the time it reaches the sewage treatment plant, most of the toilet paper has completely disintegrated and goes straight to the sludge digester tanks to be broken down into compost, along with the actual poop.

Anything more robust than toilet paper, such as flushable wipes, doesn’t break down, though, and has to be removed using a system of mesh filters, before going for landfill or incineration.

Asked by Nina Perkins, Knutsford

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Why is there poo on the Moon?

Why is there poo on the Moon? © Getty Images
© Getty Images

The Apollo landers were designed to lift off from the lunar surface at a particular weight. Since the Apollo astronauts were charged with bringing large amounts of Moon rock back home, the weight of those samples was offset by leaving behind unwanted items. This discarded junk included, among other things, two golf balls, 12 cameras, 12 pairs of boots, a gold-plated telescope, and a total of 96 bags of ‘human waste’ – urine, faeces and vomit!

Although not the best example of green thinking, this detritus will have had no permanent effect on the lunar environment. Any microorganisms present in the human waste could not have grown under the harsh conditions of the lunar surface. It is possible, however, that some could have survived for a time as dormant, inactive spores. So, after 50 years on the lunar surface the human waste, which is now probably just bags of dust, may contain important information on the survival of microorganisms in space.


Astrobiologists would like to see if any of those microorganisms have undergone any genetic mutations due to the harsh lunar environment, or have indeed survived in a dormant state. They hope one day that private companies may eventually return this human waste for study!