Chemical Monitoring Directions
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 fisheries.

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 water reservoirs.


  1. Be sure to replace the cap immediately when removing a strip from the bottle. The test strips are sensitive to moisture in the air.
  2. 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.
  3. 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.
  4. 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.