I'm trying to prevent the annoying, brown, tear-stained eye areas my Bichon puppy acquires. For those unfamiliar, this looks something like:

Not actually my dog

This article explains that these stains are commonly caused by the iron inside a dog's tears, which can be reduced by feeding a dog deionized water.

Would a common water filter (a Brita filter) provide enough deionization to prevent further brown stains, or are there alternative preventative measures?

  • What type of water source do you use? Well water, city water, tank (if so, what is the tank made of), etc.. Commented Oct 10, 2013 at 15:58
  • It's just standard tap water that we use. Commented Oct 10, 2013 at 16:00
  • The fix for our Bichon's brown stains had nothing to do with her water. What solved that was changing her dog food. We just racked our brains trying to remember what dog food caused that; but all we can remember is changing to Cesar --and some dry foods-- solved that. Sorry we can't remember, but maybe this will help. Commented Mar 24, 2017 at 2:58

1 Answer 1


The iron in your water is present in two forms. The majority of it is iron (III) oxide, also known most commonly as rust. The second is ionized iron, which is Fe2+.

Iron oxide is insoluble in water, and if enough of it is present (usually happens in well water) then the water will start to have a brown/orange tinge. It is not filtered by Brita filters. They use activated carbon filters which will not filter out iron.

Reference for this. See section called 'What Activated Carbon doesn't do'

Fe2+ is usually not present in in high quantities in water, as it is a rare form of iron, and in drinking water it is not stable and precipitates into iron (III) hydroxide, which is also insoluble and rust colored. Reference. There still some remaining though.

To fully filter out the ionized iron and the solid iron, you need a system that oxidizes the ionized iron and a filter (sediment filters are fine) to get the particles that become oxidized or were already present. More information here.

This is all very complicated and can be expensive though (unless you just want to buy a sediment filter, which can be 10-15 dollars).

A less expensive option would be to buy a large jug of water at a grocery store that was treated by reverse osmosis, as this removes most of the iron. Make sure you check out the standards of the brand you are buying though, because some filter out more things than others.

  • @mattytommo I am curious which method(s) you used, which worked the best, and how effective it was. Commented Mar 20, 2014 at 13:34
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    Hey Patrick, we actually used a product called Angel Eyes. It's a tear stain remover and I believe is predominantly kidney based. It's worked a treat and made her coat look better as a whole also! We kept the water as-is. Commented Mar 20, 2014 at 14:12
  • good point, we use this product too - but not sure how it works, maybe someone could shed some light on this (it would be a new question also )
    – poseid
    Commented Jan 18, 2022 at 12:36

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