I’ve been saying for quite some time now that I am not comfortable with USEPA’s maximum allowable level of nitrates in drinking water. This amount is known as the Maximum Contaminant Level or MCL in your water report.
Yet another study has come out which finds a causal relationship between nitrates in drinking water at just half of the MCL and bladder cancer in post menopausal women.
You can read a synopsis of that study here:
Nitrates typically come from nearby or upstream agriculture but may also come from your septic system if you are on a well. While USEPA allows up to 10 mg/l, the level at which I would be concerned is 3 mg/l. This study above finds an association with cancer at 5 mg/l.
Obtain and review a copy of your local water quality report to learn if you have nitrates in your water.
To remove nitrates from drinking water you can use either a nitrate resin, which is like a water softener for the whole house but made specifically for nitrate removal or, more commonly, people would use reverse osmosis at the kitchen sink to avoid drinking it. At high levels I personally would not bathe in it either. I don’t know whether nitrates are absorbed through the skin or not. Better safe than sorry later.