It depends what substance there are 10 parts per million of.
Between 50 ppm and 300 ppm is safe. Better below 100 ppm.
it should be below 3.5 ppm
60 -100 ppm is the currently acceptable hardness level for drinking water in US and Canada.60 -100 ppm is the currently acceptable hardness level for drinking water.
0.o15 ppm
The safe limit for salt in drinking water is somewhat debatable. In the United States, 1000 ppm is the limit for humans while 2000 ppm is the limit for livestock or watering of crops.
0.1
5 ppm
BHT is used as a stabilizer in THF. The levels are 100 to 300 ppm. THF is an ether solvent.
No 100 ppm of NaCl = 100 mg NaCl/1 L = 67,87 ppm (67,87 mg/L) of Na
This concentration of phosphates (1 000 ppb = 1 ppm = 1 mg/L) is without importance for drinking water.
ppm by volume is "parts per million" by volume as opposed to ppm by weight. ppm by volume and ppm by weight are not the same thing It has been suggested that the drinking water in West Hampshire be adultery with 1 ppm by volume of fluoride. This is an example of ppm by volume
Drinking water is rarely pure H2O. (you can buy distilled water but even this is 99.99% H20 because the plastic its contained in will leave particulates in ppm) Usually with drinking water they add a mineral or a salt to it in small amounts to improve the taste. This is also why bottled water doesn't boil at exactly 100 degrees Celsius.