[nudephil (OP)]

Cesar got in touch to ask this:
Why is tap water in Flint, Michigan dirty?
Can you help?

[ninaholm]

Waiting for answer

[chiralSPO]

These are two different questions.

How do you tell if water is clean?

There are many tests that can be done to determine the presence or quantify the concentration of specific impurities, like lead, fluoride, arsenic, sulfur etc.

There are also tests for turbidity, salinity, pH etc. etc. etc.

Why is tap water in Flint, MI dirty?

Because they built their plumbing with lead pipes. And then, when trying to treat the water for a disease (if memory serves, it was legionnaire's disease), they over-chlorinated (I think it was chlorine) and caused the pipes to begin corroding. Only traces of lead in drinking water can have profoundly negative results, especially over long time periods.

[Bored chemist]

And then, when trying to treat the water for a disease (if memory serves, it was legionnaire's disease), they over-chlorinated (I think it was chlorine) and caused t

Not quite

"In April 2014, Flint changed its water source from treated Detroit Water and Sewerage Department water (sourced from Lake Huron and the Detroit River) to the Flint River. Officials failed to apply corrosion inhibitors to the water. As a result, lead from aging pipes leached into the water supply,..."

From
https://en.wikipedia.org/wiki/Flint_water_crisis

[alancalverd]

How can  you tell if water is clean? Lack of odor. Visually clear of bugs and gunge (excuse the technical language, but this is a science site after all). Standard boiling and freezing point. No gases other than oxygen, nitrogen and carbon dioxide evolved on heating. pH = 7 when fully outgassed. No residue on evaporation. 

[Uren]

You can try this - fill a clean, clear glass with tap water.Bring the glass to the light and look at it carefully. Is the water clear or cloudy? Maybe you see some particles or is there a precipitate at the bottom of the glass? Anything that is not clear water may be a sign of bacterial contamination. When I lived in the property in Germany near the lake, people from our area bought a test to check the water.

[ricowater]

You can find out the water is clean by using a reverse osmosis filter machine.

[evan_au]

You can find out the water is clean by using a reverse osmosis filter machine.

This is one way of producing clean water (on one side of the filter).
But the problem remains: How do you tell if the water remaining on the other side of the filter is clean?

And this is an important question, because you really want this answer before you spend your precious pounds/dollars/euros on buying a reverse osmosis machine!

[evan_au]

How do you tell if water is clean?

Electrical conductivity.

If it contains dissolved salts, the water will be more conductive.
- a low level of dissolved salts is ok, but not too much!