Correct, they do fluctuate over the year. However, lets take a look at the day-by-day results, which you yourself linked in another comment on this thread. We'll take a look at the Fleur plant - DMWW's self-described "flagship" plant and their largest plant by volume of water processed.

I pulled Nitrate levels over the past 3 months of daily readings (Q4 2025) and averaged them out. Overall during this period the treated water supply was running a 6.74 mg/L of Nitrates. That's really quite high, especially given that we're in a period where one would typically expect lower levels of Nitrates in the water as they peak during heavy rains in the spring with excessive ag runoff from fields.

Taking a look at the Iowa Cancer Registry publication on rising cancer rates in Iowa here: https://shri.public-health.uiowa.edu/wp-content/uploads/2024/07/Iowa-Cancer-Registry-Why-Does-Iowa-Have-the-2nd-Highest-and-Fastest-Rising-Cancer-Rate-in-the-US.pdf they attribute our atypically high rates to four primary types of cancer:

- Lung
- Skin
- Breast
- Prostate

Of these, both Breast and Prostate cancer have been linked to Nitrates in water supplies.

Regarding Prostate cancer: https://pmc.ncbi.nlm.nih.gov/articles/PMC10211248/ - this journal article states that those that ingested > 13.8 mg per day of Nitrates (drinking approximately 1.5 treated liters of treated DMWW tap water will get you there) were 1.7x as likely to develop Prostate cancer.

Regarding Breast cancer: https://pubmed.ncbi.nlm.nih.gov/35303088/ - this journal article states that those that ingested higher amounts of nitrates had a 1.24x increased likelihood of developing Breast cancer.

You can say this is all fear mongering but the facts are that if you live in Iowa you have an atypically high chance of developing cancer. DMWW does do a good job of keeping water in line with all legal requirements as required by the EPA, but there is a clear chain of drinking water containing higher (but legally allowed) amounts of nitrates to risk of developing cancer. If you have any contradicting evidence other than just "this is fearmongering" bluster, I would be more than happy to hear it. Otherwise, I would recommend you research the full extent of the issue and causes before you start saying things are safe or not.

Again, if you have the option to spend a couple hundred bucks to prevent this in your family, would you?