If contaminated with bacteria water get evaporated and it turn becomes part of a cloud. How does this process purify it and make it safe for drinking after falling down as rain?
In: Biology
Bacteria don’t evaporate. It might not be entirely pure and safe, acid rain isn’t as big of a threat as it was, but air pollutants can absolutely find their way into rain water.
Bacteria doesn’t evaporate. So when water evaporates, it’s only water that’s going. The bacteria and anything else in the water that doesn’t evaporate at that temperature is left behind.
Rainwater is some of the cleanest water you’ll find. Yes, there will be some bacteria – the same bacteria that you breathe in.
answer: rainwater might not be very safe to drink. either due to circumstances around how the water is collected and stored to other pollutants that accumulate in the atmosphere that rainwater may carry.
https://www.cdc.gov/healthywater/drinking/private/rainwater-collection.html
https://www.livescience.com/is-drinking-rainwater-safe
>How does this process purify it and make it safe for drinking after falling down as rain?
it doesn’t so much as just disbursing contaminants to the point that they’re comparatively less harmful than other water sources. filtered water is still going to be safer to drink.
Water that is collected directly from the sky is likely to be safe to drink. There is gonna be a small amount of dirt and other particles in there, but most healthy humans will do just fine drinking “sky water.”
Rain water collected via run off from a roof or similar surface is an entirely different matter. Simply put, your roof has birdshit on it.
It depends on where you live.
While you’re not going to be overly concerned about biological contaminants chemical containment may be an issue.
So it depends on a lot of things and what you specifically by “drinking rain water.”
If you’re talking about “how does the process of rain formation clean water,” what is happening is that the body of water – a lake, a river, a puddle, an ocean – is releasing water into the air. Either sunlight or temperature differences means that the water molecules themselves turn from liquid to vapor and rise into the atmosphere. This process alone is enough to purify it, and it’s the same process by which you could boil water into a gas, collect the steam and condense it to have drinking water. The water physically leaves behind things that can’t evaporate or dissolve into air, like bacteria and other things in the water, like minerals such as salts. The water is the only thing that evaporates, and everything else is left behind. It’s part of the reason the ocean is salty, too – the water evaporates away, even though it has carried salts and minerals to the ocean. Becoming a cloud has nothing to do with the purity process – the water could simply become vapor in the air (humidity) and then it could condense onto a cold surface, like a water bottle, and you could then drink it (in theory). This happens in places like cloud forests, where clouds and humid air condense on surfaces to the point that there’s enough liquid water for an ecosystem to thrive. This process of evaporation of water from large bodies of liquid water is part of the water cycle.
Now technically, you can’t just “drink rain” because again, the “rain” part of the water cycle does nothing to “purify it.” Rain can fall through things like pollution and pick up heavy metals in smog or smoke, it can pick up ash and dust particles, it can pick up airborne bacteria, and lots of other things besides. If you collect that rain water and drink it, you’ll get sick. It’s part of why just collecting and drinking rain water is illegal in some places.
The main difference between the natural evaporation process – driven by the sun – and doing it on the stove or with a heat source – boiling water and then condensing the vapor back to being liquid – is that by nature the evaporative process driven by sunlight is slower and involves much smaller temperature gradients and lower temperatures overall, meaning what evaporates out of the ocean is basically *just* the water, allowing the rest to be left behind. When you do it on a stove, because it’s so much hotter – you’re boiling the water, it isn’t evaporating, even though both involve water going from liquid to gas – some contaminants, like chemicals, could also get enough energy to also evaporate with the water, so when you condense the water, you’d still have contaminated water. This is hypothetical of course, as you’d have to be dealing with water polluted with specific chemicals.
But yeah. The reason evaporation in the environment makes water safe is because the process of evaporation from a water body extracts water and *only water* from the water body, leaving all the dangerous stuff behind.
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