Have a question about a filter, a certification, or something you found in the water data? Send us a note. We read everything and typically reply within 2 business days.
Email waterbythebook@gmail.com.
What we can help with
- Filter fitment and certification. Which cartridge fits your fridge or system, and what it is actually certified to remove. Include the model number stamped on the unit or the old filter if you have it.
- Corrections. If a number, a certification listing, or a fitment on this site is wrong, tell us and we will check it against the source and fix it. Point us at the page.
- Data and methodology questions. How a figure in one of our studies was computed, which EPA dataset it came from, and what its vintage is.
- Press, research and partnership inquiries. Same address.
What we cannot do
We cannot tell you whether your water is safe to drink, and we do not give medical advice. What we report is what water systems reported to the EPA — that is occurrence data, not a compliance ruling and not a health verdict. For questions about health effects, talk to your doctor or your local health department. For a problem with your service, contact your water utility directly.
For what your own utility reported, the fastest answer is the Water Watchdog lookup — enter your ZIP and it returns your system’s own numbers, with the data vintage stated.