Safe water when decomposing bodies are polluting the pond

From the comments on EHD in Eaton County and a previous commenter noting that there were dead deer scattered around a farm-pond:

This makes getting emergency water from surface water very difficult.

Historically polluted water was a battle tactic.

 

A cow that died in a flood. Nobody admits to owning the cow. There it sits.

That is a topic worth discussing because floods often kill livestock and the bodies pollute the water. Sometimes material spills cause massive fish-kills. Even milk will kill fish because it consumes all of the dissolved oxygen and the fish suffocate.

Art Ludwig and Oasis Design

Art is a civil engineer whose expertise is in waste-water. 

He went to Latin American and used his expertise to help them find sources of safe water. He used Petri dishes to get actual bacteria counts of water from various sources.

So...the most challenging time to get safe water in much of the Developing World is at the start of the rainy season. Animals (donkeys, dogs, chickens, cattle, monkeys and "other primates") defecate in the open and the deposits accumulate during the dry season. They all sluice into the streams and rivers during the wet seasons. And during really heavy rains, the sheet of surface water can also run into open wells. An additional source of contamination is from wet clothing (hems of trousers) dripping into the open well.

The following text was written about a sample taken at the start of the rainy season. It was taken next to a river-in-flood and the water was the color of chocolate milk. Quoting from Art's writing:

M35 Well, pit-Freshly re-dug community drinking & cooking

Location, description, sampling technique: New well freshly (<48 hrs) dug next to M1 after it flooded, and used for same purpose. Sample taken from well-rinsed plastic water scoop.

Temperature: Turbidity: Color: Clear Smell: none detectable Taste: didn't try it

Surrounding influences: This well was about 4 m from chocolate river, 3 m from old well, which, when the groundwater level rose, filled with light brown foamy water. People collecting water waded through the river, then stood with dripping legs right by the 2 gal galvanized bottomless bucket which was the water container. This well did not have a fence.

Use of water: Was being collected for drinking (after boiling, they said) by several villagers as the sample was taken.

What do you think of this water? It was 4 m of coarse, highly permeable sand from a river chocolate brown first runoff water containing 20,000 buttwipes per swimming pool of fecal coliforms*. Would you drink it? Make tea with it?

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What I thought about this water: I felt very leery of this water due proximity to the river and the possibility of contamination from dripping legs and feet during collection.

Test results:(fecal coliforms/100 ml) 0

Other bacteria: (general coliforms) 4,933

Discussion: I was astonished at how clean this water was; I've drank untreated spring water with higher levels, without problems. This result suggests that 1) this amount of sand filtration is extremely effective, and 2), the contamination in all the wells in Maruata comes more from above than with the water from below, and that it increases with the age of the well. This was one of the cleanest wells tested, with the only possible explanation being that it was by far the most freshly dug, this factor overriding the close proximity of a huge quantity of very contaminated water.      Source

How is that possible????

The traditional wisdom is that filters function by having pores that are smaller than the particles that it is filtering out. Coarse sand has open spaces between the grains that are thousands of times larger than bacteria.

The answer is that sand (and soil) are not inert. The grains are covered with a film of microbes that actively feed on the organic matter in the water that percolates through it. Bacteria, virus, amoeba and paramecium are "organic matter" to those films. The filtering media doesn't mechanically filter out microbes. The microbes stick to the film as if it were flypaper and are digested by it...or become part of it. 

With that information, decent water could be obtained by moving 20 feet back from the water's edge and digging a pit to dip water from. It might have a vegetal taste but it would not be unsafe and would be totally bulletproof if boiled. 

* Ludwig uses an unconventional measure to help the regular people get a grip on just how dirty "wild" water can be. He calculated the number of fecal bacteria that would result if one kid who did not wipe his butt one-last-time would leave in a standard sized swimming pool. It was something like 0.1 grams of human feces (a faint smear) in 20,000 gallons of water. This is a level of pollution that rounds-to-zero for most people.