DRINKING WATER STANDARDS
___________________________________________________
pH
5.0 - 9.0
SAFE
TOTAL DISSOLVED
SOLIDS30 - 900 ppm
SAFE
ELECTRICAL
CONDUCTIVITY 0.05 - 1.5 mmho/cm
SAFE
MAGNESIUM
Less than 400 ppm Mg
SAFE
TOTAL
HARDNESS 0 – 75 ppm CaCO3
75 – 150 ppm CaCO3
150 – 300 ppm CaCO3
300 + ppm CaCO3 SOFT WATER
MODERATLY HARD WATER
HARD WATER
VERY HARD WATER
SULFATE-SULFUR
Less than 83 ppm SO4-S
DESIRABLE
CHLORIDE
Less than 250 ppm Cl
SAFE
TOTAL ALKALINITY
Less than 400 ppm CaCO3
NO PROBLEM
IRON
Less than 0.3 ppm Fe
DESIRABLE
MANGANESE
Less than 0.05 ppm Mn
DESIRABLE
COPPER
Less than 1.0 ppm Cu
DESIRABLE
FLUORIDE
0.75 – 1.50 ppm F
SAFE
NITRATE-NITROGEN
Less than 10 ppm NO3-N
SAFE
If the nitrate level is above 10 ppm, there is cause for concern. A safe
alternate source of water should be found for infants under six months of
age and pregnant mothers (because of the danger of prenatal
methemoglobinemia). A nitrate-nitrogen level over 10 ppm is less critical if
only adults and older children will be drinking the water. You may wish to
consult with you personal physician or a health professional before deciding
on a course of action. Boiling will not reduce the nitrate levels in water.
COLIFORM No Colonies per 100 ml SAFE
BACTERIA See below for further details on Bacteria
(ppm is the same as mg/L)
Drinking Water
Bacteriological Testing
The test routinely performed on drinking water to determine water purity is
the total coliform analysis. Coliform bacteria are associated with
contamination from the intestinal tract of warm-blooded animals.When these
bacteria are present in water, they may cause vomiting and /or diarrhea. Due
to this association, the Environmental Protection Agency has designated
total coliform bacteria as a standard that is used to determine water
purity. Non-coliform bacteria may also be present in water, but no sanitary
significance or limits have been placed on this group at this time.It should
be pointed out that a water sample contaminated with coliform bacteria is
not necessarily unsafe for consumption. It is only when the coliform
bacteria contain pathogenic bacteria (disease causing organisms) that the
supply is unsafe. The presence of coliform bacteria indicates that the
bacteria has been introduced into the water supply by 1) human
contamination, such as, an individual performing maintenance on the supply;
2) poor well construction, allowing surface water to seep into the well; or
3) the aquifer is contaminated. The laboratory does not distinguish between
pathogenic and non-pathogenic bacteria, therefore all samples contaminated
with coliform bacteria should be considered as unsafe for consumption.
Coliform Test report Methods
A, Coliform Density per 100 ml
The coliform density per 100 ml must be 0. Samples that contain any coliform
bacteria per 100 ml do not meet the bacteriological standard for purity.
Ideally coliform bacteria must be absent in a 100 ml sample.
B. (TNC) Too Numerous to Count
“Too numerous to count” describes a condition in which excessive numbers of
non-coliform bacteria prevent the accurate determination of coliform
bacteria. Due to the excessive numbers of non-coliform bacteria present, it
cannot be determined whether this sample meets the bacteriological standard
for purity.A replacement sample is requested.