Is Toilet Water the Same as Sink Water? What to Know

If you were stranded on a desert island, what three things would you bring? We’ve all played similar hypothetical questions games, flexing our brains to validate our choices. Here’s a good one for you: Is toilet water the same as sink water? Would you drink toilet water? What if you were stranded, not on a desert island, but in your home after a natural disaster?

Sounds pretty gross, but desperate times call for desperate measures. Let’s get to the bottom of this theoretical scenario with Tap Score water quality engineer Johnny Pujol.

Where Do Toilets and Sinks Get Their Water Supply?

“The water destined for your toilet is coming from the same source as the water heading towards your tap,” Pujol says. “It’s the same water that comes out of your sink.” In other words, it starts out clean, but that’s only before it actually hits the tank. After that, things get murky.

For one thing, Pujol says: “It is likely that your toilet tank is very rarely cleaned.”

Be honest: When was the last time you drained and scrubbed the inside of your toilet tank? If that answer is never (raises hand), the tank’s probably not pristine. After all, it is in the bathroom.

“[B]ecause of this,” Pujol says, “the water in the tank could be contaminated and it would then contaminate any clean water entering the tank.” Once the clean water meets the dirty tank, it’s game over.

As far as the bowl goes, come on now. You know the answer to this one: “Because the toilet bowl is exposed to feces,” Pujol says, “there are likely bacteria living in and around your toilet bowl that can contaminate the water.”

So the water from the pipe to the tank is (theoretically) clean, but the bowl water is definitely not. Even clean freaks who scrub the toilet bowl every day will miss something.

Additionally, older homes may have deteriorating fixtures or pipes that contribute to plumbing water quality issues, especially in bathrooms with infrequently used sinks or poor ventilation.

Understanding Water Quality Differences

The main difference between toilet and sink water is contamination risk. Both originate from the same municipal water supply but sink water remains relatively clean as it flows through controlled fixtures. However, toilet water is exposed to bacteria and contaminants in the tank and bowl, which makes it unsafe for consumption. Regular cleaning can reduce some risks, but toilet water is generally more prone to contamination.

Another significant difference is the water exposure time—sink water is applied immediately and runs continuously, minimizing the opportunity for bacteria growth, whereas toilet water tends to be left stagnant within the bowl or tank for extended periods, wherein microorganisms have ample chance to proliferate. Furthermore, toilet water can have chemical residues from cleaning agents or minerals accumulating over time, further influencing its quality.

Are There Risks in Drinking Toilet Water?

It depends, but let’s make one thing clear: “[W]e don’t recommend drinking water from your toilet tank or bowl if it can be avoided,” Pujol says.

Is that a caveat I see? Let’s say you were desperate—natural disaster, zombie apocalypse—and there was no potable water. That toilet tank would look pretty good. Could you make it work?

Well, sure. But you’d definitely have to treat it. “If you treated your toilet tank or bowl water with the intent to drink it, you’d want to focus on disinfection for bacteria,” Pujol says.

Water purifiers could theoretically clean toilet water if you really were dying of thirst. We’re not talking about a regular Brita, though. Find one that works on bacteria.

What Can You Use Toilet Water For?

Plumbing water quality issues often arise from aging pipes, poor maintenance and contamination in household plumbing systems. Corrosion in metal pipes, sediment buildup and backflow can affect water quality, making it unsafe for consumption. Contaminants from plumbing materials, like lead or rust, may also leach into the water supply. Regular inspection and maintenance are necessary for clean and safe water from taps and toilets.

Safe uses for toilet water include:

• Flushing toilets
• Watering plants (Pujol says it probably wouldn’t hurt anything, but you may want to stick to outdoor plants)

That’s it.

Seriously, folks, there are just not that many things you can do with toilet water, at least not in your home.

After it leaves your house? That’s a different story. Once flushed, toilet water heads to the wastewater treatment plant, where it’s cleaned and released into our rivers and streams or diverted to farms for irrigation.

What If My Dog Drinks Toilet Water?

It’s generally OK, but Pujol says it depends on how long the water has been in the bowl and if the bowl is clean.

Dogs have different digestive systems than humans, and they’re typically more resistant to bacterial infections. Dogs eat trash, roadkill and random chicken bones on the sidewalk, so a little toilet water is unlikely to do much harm.

“Even if the toilet bowl is contaminated,” Pujol adds, “your dog might not get sick because it takes exposure to a pathogenic strain at a high enough concentration to cause illness.”

If you’re worried or don’t want a slobbery mess, keep the toilet lid down. “We still can’t recommend giving your dog toilet bowl water on purpose,” Pujol says. “But if it happens, it’s not guaranteed to be an issue.”

FAQs

Is it safe to drink water from a bathroom sink?

Bathroom sink water is normally potable since it’s drawn from the same sanitary water source as kitchen water. But water quality might be affected by older pipes or contamination.

Why does toilet water, at times, appear cleaner than sink water?

Toilet water can appear cleaner because it lacks soap, toothpaste or hair, which are present in sink water. However, toilet water can still be infested with bacteria from the bowl or toilet tank.

About the Experts:

• Johnny Pujol is a water quality engineer at Tap Score, which is a prominent water testing and analysis company. He is an expert in analyzing residential water safety and contamination risk. With environmental health experience spanning years, Pujol gives advice on water sources, plumbing systems and treatment procedures.

Sources:

• American Water Works Association: “Reclaimed Water for Public Water Supply Purposes”
• CDC: “Waterborne Disease and Outbreak Surveillance Reporting”
• EPA: “Safe Drinking Water Act (SDWA)”
• Tap Score: “Water Testing For Your Home”