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Currently in the bay area its 60-80% humidity. It also hasn't rained for weeks. In the summer, certain parts of the Bay Area still has high humidity levels wit

Currently in the bay area its 60-80% humidity. It also hasn't rained for weeks. In the summer, certain parts of the Bay Area still has high humidity levels without rain for months on end.

f6v 5y ago
> Currently in the bay area its 60-80% humidity. It also hasn't rained for weeks. This brings back my summer Berlin memories. The temperatures are pushing 40, the air is so thick you feel like in Amazon rainforest. But no rain in sight.
mike_d 5y ago
You would need to extract 814,891,540 gallons of water to equal 1 inch of rainfall on just the city of San Francisco. Some basic napkin math says at normal temp and humidity that is roughly 84 cubic miles of air you'd need to reduce to 0% humidity. Assuming the process isn't instant, you couldn't contain that volume of air in a structure humans know how to build. You'd also have to build massive air inlet pipes going 5 miles in each direction just to be able to circulate it into the machinery. Edit: the comment I replied to was talking about areas with "humidity but not rain." I was just pointing out trying to replace rain is an insurmountable problem. You can do all sorts of things to optimize water usage, but that isn't the point. I picked San Francisco because it is a scale most people on HN can understand, but it is still tiny compared to farmland in the central valley.
- swiley 5y ago
  Air circulates naturally, this idea won't work at all for other reasons but your calculations are: 1) for the whole city when these things are usually intended for households (and cities have many miles of pipes anyway.) 2) without mention of the rate of water extraction or energy use per liter which is usually what makes these obviously useless.
- cobookman 5y ago
  Yes and No. What percentage of the rain ended up back in the ocean? Suspect a very small percentage of rain actually ends up being used by humans. You just need enough for the water that ends in taps or in the garden/farm. I'm not saying this is preferred over desal, water recycling, or other water conservation/generation possibilities.
m463 5y ago
The region between alcatraz and pier 47 might be a bit higher. Honestly I think it would be nice to have a magic drinking water creator, but wouldn't it be distilled water? (which isn't good for you, depleting minerals)

Currently in the bay area its 60-80% humidity. It also hasn't rained for weeks. In the summer, certain parts of the Bay Area still has high humidity levels without rain for months on end.

f6v 5y ago

> Currently in the bay area its 60-80% humidity. It also hasn't rained for weeks. This brings back my summer Berlin memories. The temperatures are pushing 40, the air is so thick you feel like in Amazon rainforest. But no rain in sight.

mike_d 5y ago

You would need to extract 814,891,540 gallons of water to equal 1 inch of rainfall on just the city of San Francisco. Some basic napkin math says at normal temp and humidity that is roughly 84 cubic miles of air you'd need to reduce to 0% humidity. Assuming the process isn't instant, you couldn't contain that volume of air in a structure humans know how to build. You'd also have to build massive air inlet pipes going 5 miles in each direction just to be able to circulate it into the machinery. Edit: the comment I replied to was talking about areas with "humidity but not rain." I was just pointing out trying to replace rain is an insurmountable problem. You can do all sorts of things to optimize water usage, but that isn't the point. I picked San Francisco because it is a scale most people on HN can understand, but it is still tiny compared to farmland in the central valley.

swiley 5y ago
Air circulates naturally, this idea won't work at all for other reasons but your calculations are: 1) for the whole city when these things are usually intended for households (and cities have many miles of pipes anyway.) 2) without mention of the rate of water extraction or energy use per liter which is usually what makes these obviously useless.
cobookman 5y ago
Yes and No. What percentage of the rain ended up back in the ocean? Suspect a very small percentage of rain actually ends up being used by humans. You just need enough for the water that ends in taps or in the garden/farm. I'm not saying this is preferred over desal, water recycling, or other water conservation/generation possibilities.

m463 5y ago

The region between alcatraz and pier 47 might be a bit higher. Honestly I think it would be nice to have a magic drinking water creator, but wouldn't it be distilled water? (which isn't good for you, depleting minerals)