What's in Your Tap Water? Nitrates over 10ppm?


I want to talk about what is in your tap water Before it goes into your tank. I think most experienced folk here test their water at some point instead of just trusting what comes out of the tap.

I used to work for our local municipality and my ex worked for the water plant and so I have some experience with what goes on from that end. I always test my tap water for ammonia and nitrates before water changes. The cost of the test is cheap compared to my fish. The officials are not required by law to tell you of any nasties in your water if the can fix the problem in less than 24 hours. That is a lot of hours for you to have yucky water.

The two big nasties that they seem to have a hard time with are ammonia and nitrates. Nitrates are regulated at no more than 10ppm by the EPA

But what I really wanted to stress in this post is what to do if you find high nitrates in your public tap water...

maybe we could sticky this because I keep seeing so many people posting that they are testing their tap water and finding readings of 20ppm or 40ppm... This is illegal and regulated by th EPA Your water plant will want to know and I would call them right away. These levels, if they are acurate are high enough to harm babies according the information provided by the EPA. Your water plant will test your water at your tap for free and respond accordingly. If you are not satisfied with their actions there is a drinking water hotline for the EPA 800-426-4791

I know we can fix this in our tanks... but don't just let it go in your homes. Report it. Please. We as fishkeepers are the only ones out there testing the water in our homes. No one else is likely to catch this problem and let the water companies know.

Okay, off my soapbox now.

Happy fishkeeping!


HI lorianne!

Great thread.
It's been moved to the Aquarium water section of the forum and stickied.

Thank you for the information.


I so appreciate this. I've been hyperventilating for days now, trying to piece together what is going on with our water!


Hmm... I didn't realize this until I tested my tap water... it is 40+ ppm!!! I guess I'll be calling the township water dept. in the morning. Glad I never actually drink the tap water LOL


I've been reading on this recently because our tap water is around 20-30ppm every single time I test it.

seems the Canadian regulations are different, and refer to two different ratings. They say the limits are 40ppm nitrates, but 10ppm nitrogen-nitrates.

Not sure what the difference is, or what the liquid test kit actually tests for, but.... *helpless shrug*

Taylor Horn

Mine is high too!! Should I use spring water instead of tap for water changes? I’ve done 4 50% over 4 days and my level hasn’t went down much so I tested the primed tap water and low and behold it’s almost as red as my tank water ...


I actually think this post may be wrong. The limit for nitrates in drinking water according to the EPA is 10 ppm measured as Nitrogen. (). When measuring nitrates as NO3, the limit goes to 45 ppm (https://www.waterboards.ca.gov/gama/docs/coc_nitrate.pdf).

I think measuring nitrates as nitrogen is measuring just the nitrogen part of nitrates. I think our API test kits measure nitrates as NO3, which would mean those readings of 40 ppm are actually under the legal limit set by the EPA. Which sucks, because that's still too high for fish.


Why would there nitrates in water? I have well water and we have 20 ppm nitrates from the tap. Where would it have come from? (Getting pathos for tanks because they're awesome.)

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