In case you haven’t heard over the last few years, Flint, Michigan has been in a water crisis over lead in supply pipes.

There has been all kinds of efforts and hand-wringing over what to do, who is to blame, what the government should do to fix it, etc etc.

What there has not been is actual fixes to the problem.

So let’s take a stab at it.

According to the WHO, the needs for water for a person are about 70 liters per day.

https://www.who.int/water_sanitation_health/publications/2011/tn9_how_much_water_en.pdf

Let’s get crazy and round it off to 100 liters per day per person.

Per the Google, the population of Flint is 96,448. Pretty close to 100k.

100k people, 100L per day each makes for 10 million liters of water per day.

Seems like a lot.

Now let’s think for a moment. The municipal water system has completely failed. So how can we get water without using the city system? Rainfall seems like the obvious answer.

According to https://www.usclimatedata.com/climate/flint/michigan/united-states/usmi0295 Flint gets about 31 inches of rain per year. The winters are about half as wet as the summers, but there are about 36 inches of snow per year and 120 days of precipitation

So let’s do some quick math.

Let’s say each precipitation day has only an hour of precipitation. I know storms take longer than that, but it will make for a very conservative estimate.

That means that those 31 inches of rainfall in bursts of 0.26 inches of rain per hour, which equals 6.5 mm of rain per hour 120 times, or 0.11 mm per minute over 7,200 minutes.

Let’s call it 0.10 mm per minute and consider that one unit of rainfall.

OK, now we need to obtain 365*100 liters over 7,200 rainfall minutes. That means we need to capture 5 liters of water per rainfall minute. 5 liters is 5,000,000 cubic mm. If the rain is falling at 0.10 mm per minute, that means we need 50,000,000 square mm or a square 7120 mm on a side to capture that 5 liters.

A square 7120 mm on a side is about 23 feet on a side. So if you had a tarp that is 23 feet on a side and had it all funnel to a cistern tank, then you could capture enough water from rain to supply all your needs in Flint.

If the rains actually last longer than an hour, then you can shrink that tarp. If you capture some of that snowmelt, then you can shrink that tarp. You’d probably end up with something half as big in catchment area and still be fine.

Or you could go full earthship style with water recycling and cut the area required by a factor of 5.

Filter that water and you’re good to go.

Total investment? Something like 1000 USD per person for materials, tanks, and filters. In bulk, I’m sure you could get that cost down quite a bit. 100 million USD for the whole city. It’s simple, it’s ecologically friendly, and it would be fast.

So why hasn’t this been done?

Lots of reasons.

For one, it doesn’t work for apartments. They don’t have enough horizontal area to catch enough water.

For another, it’s an individual solution. Nothing is stopping every single family home from implementing this right now. But the overwhelming majority don’t. We want our centralized solution. We want it done for us.

A decentralized solution means individual responsibility. And that’s a symptom we have been conditioned out of a long time ago.

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