True Companions VetVan
In-home veterinary services in the Twin Cities, MN since 2010

"The Scoop" Blog

Water for Thought


Sometimes danger lies where we least expect it, even in the stuff we can't live water and salt.

A local veterinary specialist recently mentioned to me that he has seen a significant increase in incidence of kidney and adrenal diseases in pets, which he contributes to drinking water from a water softener. This is a fascinating (and somewhat frightening) observation—but can it be verified?

Unfortunately, I’m not aware of any way to actually track the incidence of kidney or adrenal diseases in the area —veterinary medicine simply doesn’t have any centralized database to follow these kinds of trends. So, although I consider this individual to be very credible, I really can’t confirm his observation on the incidence of disease. However, is it possible that ingesting water treated with a water softener could pose a health risk to pets (or people)? THAT seems like something worth investigating!

What's the Deal with Hard Water and Water Softeners?

Water is considered “hard” if it has a high concentration of minerals, particularly calcium and magnesium, which end up in groundwater by dissolving from surrounding rock and soil. While these minerals are safe and non-toxic, the dissolved minerals can, over time, build up in your pipes and fixtures, creating “scale”. This scale can reduce flow through the pipes, even to the point of completely clogging them. Hard water also interacts with soaps to reduce their ability to lather up, making it more difficult to clean, and to create sticky “soap scum”, which is just straight up nasty on your fixtures.

Water hardness varies tremendously based on where your water is coming from. A community water system (CWS) is required to complete an annual Consumer Confidence Report (CCR), which includes full information on water quality, including hardness. This information should be readily available from your water provider, which for most of us in the metro area will be your local municipality. Water hardness is measured in grains per gallon (gpg). Water with 7 to 10 gpg is considered to be “hard”.  Over 10 gpg is considered to be “very hard”. For most communities in the Twin Cities metro area, water hardness is reported to be between 17 and 22 grains per gallon!*

There are a variety of ways to reduce the hardness of water, but the most common is to use a water softener. This happens via chemistry — yep, your high school chemistry teacher was right. You really DO need to know some basic chemistry! Most softeners use salt (sodium chloride) to “swap” the magnesium and calcium ions dissolved in the water for sodium. Sodium doesn’t build up in plumbing or react badly with soap, so it is considered to be more desirable in your water. This process is called ion exchange.

So, Should Your Pet (or You) be Drinking this Softened Water?

The amount of sodium added to the water in this process is generally considered to be safe. However, that amount depends on the “hardness” of the water to begin with. For every grain of hardness removed by a traditional water softener, 8 milligrams of sodium is added per liter of water. So let’s do some math (yep, your math teacher was right, too).

I went to my local city web site (Cottage Grove) and looked up the most recent Water Quality Report (2012).  It reports the hardness to be 17 grains per gallon (gpg), well in line with most communities in the area.

So if 8 milligrams of sodium is added per liter of water for every grain of hardness removed, that means that my water softener is adding 136mg of sodium per liter(8 X 17= 136). My local water report shows that the sodium in the untreated water averages about 9.5 mg per liter.  So the water softener is increasing sodium in my water by over 140%!

So what does that mean? People should drink between 1 and 4 liters of water every day, depending on their age, sex, and health status. So an average person drinking 2 liters of water every day will be adding 272mg of sodium (136 x 2) to his or her diet by drinking softened water rather than unsoftened. The Food and Nutrition Board of the National Research Council recommends that most healthy adults limit sodium consumption to no more than 2400 mg/day. Based on that, 2 liters of softened water in Cottage Grove will make up approximately 11% of your daily recommended sodium intake. Certainly this water is still well within the guidelines of a “low sodium beverage”, but you can see that it is not insignificant — particularly in an individual who is limiting salt intake for health reasons.

The answer gets a bit cloudier when we discuss our pets. Research is not clear on how much sodium is too much in a dog’s or cat’s diet, so we really don’t know what a maximum recommended sodium intake should be in our pets. The AAFCO (Association of American Feed Control Officials) recommends that cats consume approximately 0.3mg of sodium per kcal of metabolizable energy, or ME (that’s nutritionist lingo for calories) ingested per day; some early research has shown reduced kidney filtering with either too much or too little sodium ingestion in cats. So let’s do some more math!

An “average” 10 pound adult, neutered, healthy cat with an “average” activity level needs to ingest about 250ml of water every day. Based on our earlier calculations, we know that my water softener is adding about 136mg of sodium per liter of water—which is 0.136mg per ml of water. So my 10 pound cat will take in an additional 34mg of sodium with his softener- treated water. That same kitty will need to eat about 250 kcal per day. So using the AAFCO guideline of 0.3mg of sodium per kcal ingested, he should have 75mg of sodium per day (250 X 0.3). So his softener-treated water is adding nearly 50% of his recommended sodium intake!

The picture is even MORE cloudy for dogs, because we don’t have any established sodium intake guidelines. However, a 50 pound, healthy neutered adult dog should be ingesting about 1200ml of water a day. Water treated with a water softener will add a bit over 163mg of salt to his diet.

But Wait! There's More!

There's more to consider than just sodium ingestion. The body requires a precise balance of water and other chemicals, including sodium, to function properly. Too much or too little, and things start to fall apart. If the water ingested contains more sodium than the cells, the cells of the body will have to release water in order to balance out the excess sodium particles. So drinking water with an excessive sodium content will actually dehydrate the body.

One of the key functions of the kidneys is to filter out waste and excessive chemicals from the blood stream. Flushing out excess sodium will require large amounts of water. Thus water is lost in the urine, along with the excess sodium particles. If this continues, the excess water loss can overwhelm the kidneys, leading to kidney failure.

So, What's the Verdict?

Clearly there is a lot we don’t know about all of this, but the calculations seem compelling to me. I can tell you that my family — both 4- legged and 2 — will be drinking water which is not treated with my water softener. 

In fact, this is already true. I know that when my water softener was installed, the installer bypassed the cold water tap to my kitchen sink so kitchen sink water is unsoftened, as is the water flowing through our drinking water filter. Since all of our water for cooking and drinking come from the kitchen sink or filtration system, we’re already all set. This is true with most water softener installations, but you should verify with your installer.

* The most complete chart of water hardness I was able to find was listed at this website:  Although this is provided by a private company, the numbers are readily available from each municipality. They just did some leg work for me. You should verify this information for your local area.
Shane Longtin