Hach Nitrate/Nitrite Test Strip Instructions
Prepared by Deana Crumbling
The Hach Test Strip is a quick, simple, and safe way to estimate
the concentration of nitrate and nitrite in stream water. Nitrate
(NO3-) and nitrite (NO2-) are forms of inorganic nitrogen that
are very soluble in water and are readily taken up by plants.
Nitrate is more common in streams than nitrite. The nitrite result
will usually be "0" in streams unless the stream is
being heavily impacted by a pollution source. Once in a while
the nitrate result may be "0", but usually the result
will be "0-1". The nitrate result may be higher than
1, especially if the water sample is taken when (or where) there
is a lot of runoff entering the stream. Results higher than 5
should be double-checked, and reported for a follow-up investigation.
Increased amounts of nutrients in surface water cause algae
blooms, which in turn cause other problems for streams. Increased
levels of nutrients in Fairfax County streams reach the Chesapeake
Bay where they contribute to the destruction of Bay habitat and
In Fairfax County (where agriculture has been largely replaced
by suburban development), fertilizer runoff (from lawns and golf
courses) is the predominant source of nitrate to streams. The
presence of nitrate from fertilizer also indicates that other
applied lawn chemicals directly toxic to stream ecosystems, such
as herbicides and insecticides, may be running off into streams.
Another chronic source of nitrate addition is the atmospheric
deposition of automobile emissions to impervious surfaces. Stormwater
runoff then carries the excess nutrients directly into streams.
Leakage from sewer lines running alongside or under streams
can cause very high levels of nitrate, and the nitrate can be
used as a marker to localize the leak. Septic systems can also
leak nitrate into nearby streams. Sewage leaks can contribute
harmful bacteria and viruses to streams that drain into drinking
- Be sure to replace the cap immediately when removing a strip
from the bottle. The test strips are sensitive to moisture in
- Hold a test strip by the bare end. When dipped in water containing
these nitrogen species, the pads will develop a pink color, which
is matched to the color blocks on the outside of the bottle.
Do not hold a wet test strip against the bottle. The water will
ruin the color blocks and make them difficult to read.
- A test strip is dipped into the water for 1 second. You can
collect a fresh water sample in a clean container or dip the
strip directly into the stream.
- Time for 30 seconds and then look at the nitrite test pad
on the strip. If there is no pink color, the test is negative,
and the result can be recorded by circling the "0"
in the nitrite row. If there is pink color, but it is not as
dark pink as the 0.15 color block, circle the "0-0.15"
option on the Sheet. If the pink color looks exactly the same
as the 0.15 color block, circle the "0.15" option on
the Sheet, and so on. At 60 seconds after dipping the strip,
match up the nitrate test pad in the same way, and circle the
appropriate option on the Sheet.