Microscopic Life Sensor

Anything from a bench-top microscope to a Total Organic Carbon analyser will fit the bill, Mildred.

Heat your water to 161°F for 30 minutes and call me in the morning....

http://newatlas.com/bacteria-water-sensor/39794/

It sounds as if this is untreated surface water.

If yes, I would believe that it is almost a certainty that microscopic life - bacteria, amoebae, small eggs, and other critters - are in the sample.

If no organisms are present, I believe it is a certainty the sample is unfit for human consumption.

If you want to get really fancy ... http://www.futurity.org/dna-shorelines-puget-sound-1251392-2/

Sorry can't resist the self referential play on words:-

"can make you very sic if you drink the water." (sic.?)

A small microscope shows tiny critters swimming around in "swamp water".

Maybe a video microscope connected to a computer and software which would take a picture periodically and compare successive shots. It should trigger when "something" swims by.

Sounds like an interesting project.

There might be video security software out there that has "motion detection" that might be useful for this application.

Not sure how many amoeba will make aggressive motions resembling a home invasion squad, or a burglar.

No need to re-invent the wheel on this one, it has been invented already.

Don't drink water that isn't potable.

If I don't know for sure that the source is "OK", these seem to work well.

Logic and eyes are your best sensor.

Logic dictates that there always is and will be bacteria.

Eyes can tell you if you at least are holding a bottle of distilled water in hand.

If you ask me I was not even sure if distilled water would be free of bacteria.

They cling to the bottle wall like spider silk to hair.

I'm sure that HACH and other equipment suppliers could provide a "Total Organic Carbon" test device with sequence time in the order of 1 minute. This will tell you whether carbon based material is present, but not whether it is curently "alive" at the time of testing.

This would give you a go/nogo outcome.

In the water processing indusry, current best practice for pathogens is a 24 hour incubation process using multiple cells and a nutrient additive to enhance organism growth.

TOC is no indicator of potable or not potable. You could get a low TOC reading, and still have pathogen organism present that will kill you.

This would depent on what they selected as their go/nogo decission point.

I'm suggesting a TOC that may be acceptable in water with residual chlorine and other known treatments would NOT be the threshold used in such a review for water of unknown origin.

TOC could also indicate the presence of some toxins from previously living organisms that would not show in culture or microscope examination.

You and I both know that he really needs a treatment system with independant barriers, backed up by an analysis system that is planned and verified. He may not have the resources to move that far from his curent situation and is at least looking to move to an improved situation.

In that case, he does not need a sensor, he needs chlorine, and a lot of heat. Boil it and be relatively safe.

That's right, and it works both ways. A cup of tea with milk has high TOC, COD, BOD etc but won't kill you!

The good the bad and the ugly.....

http://extoxnet.orst.edu/faqs/safedrink/microorg.htm