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Comment by chmod775 | Hacker News Reader

>Fresh water cost $1 per cubic metre.

That really depends on where you are, infrastructure, and economies of scale. The statement is ridiculous by itself.

If I pumped a cubic meter of drinking water here and mailed it to you, it would cost much more than $1. If I instead built pump and piping from scratch to provide you with a single cubic meter at your location, it would also cost way more. Especially if I could source neither parts nor know-how locally and instead had to ship them around half the globe.

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> That really depends on where you are, infrastructure, and economies of scale.

Yup. For example in Finland it costs between 1-3€/m3 depending on where you are in the country.

Then again it's "the land of a thousand lakes" and while most of the water isn't drinkable (at least according to "health standards", anymore, due to human activity) you can still drink from the lakes/streams in Lapland. And there are aquifers everywhere.

We've somewhat created this problem ourselves. Back in the day you wouldn't even consider settling anywhere without a reliable water source. Nowadays if the environment can't support you we'll just come up with some high-tech solution and have more babies and in the process we become dependent on state infrastructure. People like Elon Musk want higher tech and more people, and while I'd like to agree with him I don't see that as realistic, given human nature and the current landscape around the world.

Ok, that was a bit of a derail.

I really like innovation like this though. As long as someone can supply the materials for the device, it really improves quality of living in many places.

This isn't high tech stuff. People all around the world know how to make clean water. It doesn't require specialised equipment or knowledge.

https://en.m.wikipedia.org/wiki/Slow_sand_filter

A slow sand filter requires water that is not salty. A desalination device serves a different purpose.

I know off of the top of my head how to make a very basic solar still.

The device in the article is a slightly less basic solar still.

Are you an expert in the field of desalination? Are you sure that a sand filter is a good tool for desalination?

I think I need to be more long form because people are getting the wrong idea. Desalination from seawater is almost never required, brackish sources are more common. For this multistage flash distillation is the cheapest option, reverse osmosis next. Even then most people could recycle grey water rather than run desalination. A sand filter works for this. These types of gizmo based approaches just strike me as incredibly naive as to the underlying causes of problems with water supply. More than naive, patronising. People in poor countries aren't stupid.

+1. Reminds me of Gandhi proposing that Indian households "solve" the problem of importing clothing by spinning their own cloth at home, which is ridiculously impractical compared to letting factories do an incredibly tedious and time-consuming job.

> are you an expert

Appeal to authority is not an argument

Agreed, but it might indicate us wether we should take the answer with a …pinch of salt.

I don't expect this to work in areas were typically desalination is used, since there is no freshwater available there.

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