Nitrate Watch logo

Nitrate: The Basics

Where does nitrate come from?

Nitrate is formed when nitrogen combines with oxygen in water. It occurs naturally in plants, including in many vegetables that we eat. It also comes from human-made sources, including fertilizers, animal feedlots, and sewage. Nitrate dissolves in water and can easily be carried by rainwater and melting snow until it reaches surface water or groundwater. When there are elevated levels of nitrate in a water source, that’s almost certainly because of human-made contaminants.

Why is excess nitrate bad for human health?

When we consume too much nitrate, that can make it harder for our blood to transport oxygen. In infants younger than six months, that can lead to a condition called methemoglobinemia (or "blue baby disease"), which can cause the skin to turn blueish-gray and may lead to serious illness or death.

Ongoing research has found that other health conditions are also linked to consuming high levels of nitrate. Peer-reviewed studies document increased risk of colon cancer, thyroid disease, and neural tube birth defects, like spina bifida and anencephaly, in populations with prolonged exposure to drinking water contaminated with nitrate. What is even more concerning is these health effects are observed when the nitrate levels in drinking water are lower than antiquated federal drinking water standards allow.

If plants need nitrogen to grow, why is excess nitrate bad for the environment?

Too many nutrients is a bad thing. When excess nitrate is present in waterways, it may overstimulate the growth of algae, creating what is known as an algal bloom. This not only encourages the formation of unsightly "scum" on the water, but can also have a myriad of negative effects on the environment. When the algae die and decompose in the water, the decomposition process consumes oxygen. This depletion of dissolved oxygen makes it harder for animals to survive in the water. The result is a dead zone, which in turn leads to fish kills and overall decreased plant and animal diversity.

Algae blooms also threaten human health. The drinking water supply for more than 250,000 residents of Toledo, Ohio, was shut down for days a few years ago due to a huge algae bloom in western Lake Erie. Algae blooms may harbor toxic cyanobacteria (“blue-green algae”), which can be dangerous or even deadly to people or pets. Red tides, a type of harmful algae bloom common in coastal areas, make people and pets sick and require beaches to be closed for days – even weeks – at a time.

Are there any MORE reasons I should be concerned about nitrate levels?

Clean water is not optional, and it is not free. When high nitrate levels are present in waterways that are used for drinking water, the law requires drinking water utilities to remove the excess nitrate to meet drinking water standards. This can be done with nitrate removal technology, but this infrastructure is expensive to install and operate. These costs are then passed on to ratepayers. Depending on the size of your community and the amount of nitrate in your water, you could be paying up to $1,200 a year, just to filter out the excess nitrate that shouldn’t be there in the first place.

What if my water comes from a well?

If you get your water from a well, like an estimated 43 million other Americans, you could be at risk. The EPA does not regulate private wells, nor does it provide recommended criteria or standards for individual wells. Moreover, states do not regulate well water for contaminants like nitrate. Nitrate is impossible to detect by sight, smell, or taste. The only way to know if your well water has elevated levels of nitrate is to test it.

I don't live near an agricultural area. Should I still be concerned about nitrate pollution?

Yes! There are plenty of non-agricultural sources of nitrate, including antiquated sewage treatment plants, malfunctioning septic systems, landfills, and residential and commercial properties (like golf courses) that apply large amounts of chemical fertilizer.

Your Nitrate Watch Test Kit

What comes in my Nitrate Watch test kit?

Your kit will include a bottle of 25 easy-to-use test strips, plus two postcards with all the information you need to take nitrate readings and submit your results. To use your kit, you'll need access to a stream, and a computer or smartphone so you can submit your findings.

Why do you need my address?

We need your address to send you a Nitrate Watch kit. Your personal information will not be shared outside the Izaak Walton League.

What kinds of water sources can I test with my Nitrate Watch kit?

You can use your Nitrate Watch kit to test surface water (rivers, lakes, streams) as well as tap water from public water systems and private groundwater wells. When you report your data, you can indicate which type of water source you tested.

Pick water sources that are meaningful to you for recreation, drinking or conservation! Test multiple locations so you can compare the results – but also save some strips to test the same locations again later and see how nitrate levels have changed.

Can I sample brackish water with my Nitrate Watch kit?

Yes! We have verified with the manufacturer that the Hach Aquacheck Nitrate-Nitrite test strips can be used to measure brackish/estuarine waters.

When should I use my Nitrate Watch kit?

You can use your kit any time you can safely approach a waterway, but it's especially important to test nitrate levels around the time of events that cause those levels to change. Peaks in nitrate levels are largely dictated by land use practices. For example, millions of tons of nitrogen fertilizer and manure are applied to farm fields every spring. Heavy spring rains cause large amounts of nitrogen to run off into nearby streams, rivers, and lakes. In many suburban and urban communities, sewage treatment plants become overwhelmed with stormwater during thunderstorms, resulting in the discharge of untreated sewage into adjacent waters.

How often should I use my Nitrate Watch test strips?

Nitrate Watch does not require you to stick to a specific sampling schedule. We recommend that participants establish some kind of routine (whether that be weekly testing, bi-weekly, monthly, or something else) but it is okay if you deviate from the routine as long as you are still using your strips and submitting data. The interval between sampling will likely be dictated by how many sites you plan to sample and your ability to access those sites. For instance, if you only plan to sample one spot at a stream close to your home, you could sample once per week and have 25 weeks' worth of data from a single bottle of nitrate strips. If, on the other hand, you want to sample five locations along a stretch of a stream that is a little less convenient to access, you might sample once per month and get five months' worth of data from a single bottle of nitrate strips. Both types of sampling are valuable.

The Make A Plan worksheet is a resource we’ve created to help you strategize about when and where to use the 25 strips in your Nitrate Watch kit.

Whatever you do, make sure to use your test strips before their expiration date (located on the bottom of the bottle).

Can I collect water and test it later?

Yes. Nitrate Watch lends itself well to testing water that's been previously collected, since nitrate concentrations shouldn't change significantly in water that's been taken from its original source.

Some considerations:

  • Use a plastic or glass container (with a lid, of course!)
  • Make sure the container and its lid are clean and have been rinsed with the water you're testing. We recommend filling up and emptying the vessel three times to ensure that it doesn't have any residual water left from a previous test.
  • Make note of the exact location where the water was collected as well as the date. You'll need this information when you enter your data into the Clean Water Hub.

I need more help understanding how to do this test.

This video demonstrates the entire Nitrate Watch test.

Understanding and Using Your Results

How do I submit my results?

Submit your results to the Clean Water Hub! Check out our step-by-step instructions on how to submit your data, or view a video tutorial for uploading your data using a computer or a smartphone.

How much is "too much" nitrate?

The drinking water standard for nitrate as nitrogen is 10 mg/L (equivalent to 10 parts per million), as established by the Environmental Protection Agency in the 1990s. Current research suggests that prolonged exposure to nitrate levels below 10 mg/L can still lead to increased health risks.

While EPA does not provide a standard for nitrate in lakes or streams, consistently high nitrate readings (over 10 ppm) may be cause for concern in all surface waters.

My results don't indicate that there are high nitrate levels in my community. Should I stop testing?

No! All data is valuable. Even if there is not a known nutrient pollution issue in the waterways you are testing, it is important to gather baseline data. This will make it easier to pinpoint a pollution problem should one arise in the future.

What should I do if my drinking water has high levels of nitrate?

If you find that a source of drinking water contains more than 10 mg/L of nitrate, contact a licensed well contractor or your public system operator to help identify next steps. Refrain from drinking this water until nitrate levels have decreased to less than 10 mg/L. Obtain drinking water from a safe source, such as bottled water. Boiling contaminated water will not remove the nitrate.

If infants less than six months of age, or people who are pregnant or nursing, have consumed the contaminated water, contact a healthcare provider immediately.

I found out that excessive nitrate is a problem in my community. What can I do?

There are lots of ways you can take action to protect your drinking water and local streams! Visit our What You Can Do  page for ideas and resources.

Other Questions

I already have nitrate test strips. Can I participate?

Of course! If you already have access to nitrate test strips (we use these ones from Hach), you’re all set. Just download the following postcards, which are included in every Nitrate Watch kit, and you will have all the information you need to participate in Nitrate Watch.

I already participate in Save Our Streams Chemical Monitoring. Do I need to submit my nitrate data in both places?

We took care of that for you! All the nitrate data that is submitted as part of SOS Chemical datasets is already incorporated into Nitrate Watch. No need to submit the same data twice.

Will I be able to participate in Nitrate Watch if I am colorblind/vision impaired?

Reading a nitrate test strip requires the user to make a judgment about the intensity of the strip’s color, comparing it to a list of options of varying intensity. Many people, even those without a diagnosed vision impairment, find this difficult. Our advice – get a second opinion. Bring a friend with you to monitor or snap a picture (right at 30 seconds!) of your test strip next to the color comparison chart. You can share this photo with a friend or email it to nitratewatch@iwla.org to get your second opinion.

The Izaak Walton League of America has an application pending with the U.S. Patent and Trademark Office to register Nitrate Watch.