What’s in Your Dog’s Water Bowl?

A study of microbial contamination of household items found that dog water bowls were the 4th most contaminated item in the home, after kitchen sponges / dish rags, kitchen sinks, and toothbrush holders!  (https://www.nsf.org/blog/consumer/clean-germiest-home-items). Worse yet, a UK study found water bowls to be the 3rd most contaminated household item. (https://pure.hartpury.ac.uk/en/publications/microbiological-assessment-of-canine-drinking-water-and-the-impac).
So, what’s actually in that bowl?
Bacteria, yeasts, molds, and parasites have been recovered from water bowls.   Studies have shown that the organisms present include those from feces, skin, and mouth. Many of these are known to be capable of causing infectious disease in our dogs – and in the people they live with. Low level contamination may not be a huge risk from a household water bowl as the organisms typically originate from the dog itself.  However, without proper handling of bowls to limit bacterial growth, the concentration of  bacteria can rise to levels with potential to cause disease.  Here are just some of the organisms recovered.
·       E. coli
·       Salmonella
·       MRSA
·       Serratia marcescens
·       Yeast
·       Molds
All concerns about home water bowls are magnified many times over when we think about communal water bowls as additional microbes are of concern and may be passed from other dogs to previously uninfected dogs.
·       Parvovirus
·       Canine Influenza Virus
·       Intestinal parasites such as worms and coccidia
·       Giardia
·       Canine Papilloma Virus….and more

How do water bowls get contaminated?
As the dog drinks, saliva from their mouth gets into the water.  Facial fur gets wet allowing transfer of dirt and other contamination from the fur to water. Some dogs like to put their paws in the water and play with it – paws may carry dirt, feces etc. into the water.

The type of bowl matters
The material a bowl is made from makes a difference. Smooth surfaces are less able to support bacterial growth. Irregular surfaces, scratches, cracks, and chips will create spaces for organisms to take hold, survive and reproduce.

Stainless steel
Good quality stainless steel is the best option in terms of microbial contamination. It is easy to clean and disinfect and not prone to cracking or chipping which may leave areas that are difficult to clean and enhance bacterial growth. It is important to avoid use of abrasive cleaners that may scratch the surface.  There are some risks associated with metal bowls.  Bowls produced in China have been found to contain lead and or radioactive material. A 2013 recall by Petco was caused by radioactive Cobalt-60 found in food/ water bowls.  Likewise, avoid purchasing bowls from discount stores as there is very high likelihood that these are produced under unsafe manufacturing conditions. Some dogs may dislike stainless steel bowls especially if dog tags impinge on the bowl as they drink.


Glass comes second in terms of safety for risk of microbial contamination. The main concern with glass bowls is chipping and cracking which can cause injury to the dog or make the bowl more vulnerable to contamination.  Like stainless steel bowls, glass bowls have been found to include non-food safe substances when produced by companies not following Good Manufacturing Process (GMP).

Like glass bowls, ceramic bowls are easy to clean but also prone to damage resulting in chips and cracks. Chips and crackling of the glaze will expose the porous clay underneath and support enhanced bacterial growth.   Some studies have shown that ceramic bowls are the best at supporting the growth of biofilm which in turn creates an environment that enhances microbial growth and survival.  Ceramic glazes often include lead and other toxins. Ceramic items must be certified as food safe for human use but there is no such requirement for bowls intended for dogs, so choosing a ceramic bowl that is designated for human use or explicitly labelled as ‘food-safe’ is important.

One study showed that plastic bowls had the highest bacterial count compared to stainless steel, glass and ceramic options They are also prone to scratches and damage that will facilitate the growth of micro-organisms.  Plastic bowls may also contain phthalates, synthetic estrogens, such as BPA, and other toxic substances that may leach into food or water and be ingested.  Plastic bowls can also cause Plastic Dish Nasal Dermatitis which is due to p-benzylhydroquinone in the plastic. This substance inhibits production of melanin which is responsible for the black pigment in the nose. Affected dogs develop pale / pink discolouration of the nose.  Chin acne is another issue that is sometimes seen with plastic water bowls.

Aluminum bowls are not considered safe due to the risk of aluminum leaching into water and the being consumed and absorbed.  Anodized aluminum may be safer, but it is likely best to avoid aluminum all together

Silicon is an inert substance and makes a good water bowl. Silicon bowls are great for travel purposes but generally not practical for daily use as they are not rigid and therefore more prone to tipping, being squished, and spilling.

Recently, along with the increasing popularity of bamboo as a renewable resource, bamboo bowls have become available along with innumerable other bamboo products. They are described as eco-friendly sustainable, biodegradable and durable. When using bamboo bowls, it is important to make sure the bamboo is grown without the use of toxic substances (some have been found to have toxic fillers) and that the coating is food safe. Care must be taken to avoid scratching the coating. Bamboo bowls tend to be light weight so may not be the best choice for dogs that like to play in their water bowl.





What can we do to reduce the risk to reduce risk of microbial and chemical contamination?
1.     Purchase bowls (stainless steel, glass, or ceramic) made in Canada or the USA.
2.     If using ceramic bowls, use only items certified for human use (food safe).
3.     Do a complete water change daily.
4.     Clean daily with soap and water and mechanical scrubbing (using a nonabrasive cloth or brush) to remove biofilm.
5.     Avoid use of cleaning items that could scratch the surface of the bowl (steel wool, abrasive cleaners).
6.     Monitor glass and ceramic bowls closely for damage  (chips, cracks, cracked glazing) and discard damaged bowls.
7.     Sterilize bowls with bleach regularly (e.g. 2-3 times weekly).
8.     Adding a small amount of white or apple cider vinegar to the water (1 tsp per liter) increases the acidity of the water and helps inhibit microbial growth.
9.     Avoid water bowls with large reservoirs that are designed for multi day use.