The Tankless Smart Toilet Trap: Why High PSI Doesn't Mean Strong Bidet Pressure

When shopping for a smart toilet, you’re faced with a critical, and often misunderstood, design choice: do you get a model with a visible tank, or do you opt for the sleek, modern, tankless design?

The allure of the tankless toilet is undeniable. Models like the SWAN S-Pro TA-861DF (ASIN B0BS9YMPZS) are a perfect example—they are compact, minimalist, and loaded with features like auto-opening lids and foot-activated flushing. They look like the future.

But this futuristic design comes with a hidden catch, one that is perfectly captured in the user reviews for this exact product. A frustrated 2-star review notes:

“The water pressure from the bidet is very weak. I reached out to customer support… they suggested increasing my home water pressure. I raised it to 72 psi, which is quite high, but it made no difference… the Ove’s bidet pressure is about five times stronger.”

This is the mystery. How can a toilet with 72 PSI—which is very high pressure—still be “very weak”? The answer is that the problem isn’t pressure (PSI), it’s flow rate (GPM). And understanding this difference is the single most important lesson before buying any tankless smart toilet.

The “PSI vs. GPM” Trap: A Lesson in Plumbing Physics

Most homeowners are familiar with PSI (Pounds per Square Inch). We think of it as the “strength” of our water. But there’s a second, more important metric: GPM (Gallons Per Minute), or flow rate.

Here’s the simplest analogy: * PSI (Pressure) is the speed of the water. Think of it as a Ferrari. * GPM (Flow Rate) is the volume of the water. Think of it as an 8-lane highway.

A tankless toilet’s powerful bidet and flushing system is like a fleet of 18-wheelers. It doesn’t just need to go fast (PSI), it needs a massive highway (GPM) to deliver a huge volume of water instantly.

Your old toilet didn’t need this. It had a giant tank on the back, which acted as a reservoir. It spent three minutes slowly filling that reservoir, and when you flushed, it dumped that entire 1.6 gallons at once.

A tankless toilet, like the SWAN S-Pro, has no reservoir. It must draw all the water it needs, instantaneously, directly from your home’s pipes.

Solving the Mystery of the “Weak Bidet”

Now, let’s go back to that user review. The homeowner had 72 PSI (a very fast Ferrari) but “weak bidet performance.” This almost certainly means their house has old or narrow 1/2-inch pipes. They have a Ferrari, but they’re forcing it to drive down a narrow, one-lane country road. The speed is there, but the volume (GPM) is choked off.

This explains why “it made no difference.” Cranking the pressure (PSI) from 60 to 72 doesn’t widen the pipes. It just makes the Ferrari engine scream louder.

This also explains why the 5-star reviews for the same product mention calling customer service. One user, who praised the “outstanding service” from “Ben,” had the exact same problem. The plumber and Ben (via video chat) concluded: “the problem was not with the toilet but rather low pressure in the house.” (They likely meant low GPM, a common confusion). Ben ultimately offered a full refund because the user’s house was incompatible with the toilet’s technology.

This isn’t a design flaw in the SWAN S-Pro TA-861DF; it’s a fundamental requirement of all tankless bidet toilets, whether they are from SWAN, Toto, or Kohler.

What About the Features? (If Your Plumbing Can Handle It)

If your home does have a high water flow rate (e.g., modern 3/4-inch supply lines), then you can fully appreciate the luxury features these toilets offer. The SWAN S-Pro, for example, is a showcase of “all-in-one” design: * Hands-Free Operation: A motion sensor for the auto-opening lid and a foot-activated sensor for flushing and closing. * Total Comfort: A heated, adjustable-temperature seat. * Personalized Hygiene: The bidet itself, a warm air dryer, and deodorization. * Smart Control: A wireless remote and an “App Enabled” interface for saving preferences.

These features are what make the product “top tier” to the 5-star reviewers whose homes were compatible.

The Litmus Test: Before You Buy ANY Tankless Toilet

Do not buy a tankless smart toilet—from any brand—until you test your home’s water flow rate. You don’t need a plumber; you just need a 5-gallon bucket and a stopwatch.

Go to the bathtub or shower nearest to your toilet installation. Turn the cold water on full blast and time how long it takes to fill the 5-gallon bucket. * Under 30 seconds (10+ GPM): You have a plumbing superhighway. You are ready for a tankless toilet. * Over 45 seconds (< 7 GPM): You have a country road. You should not buy a tankless toilet. You will be disappointed. Stick to a high-quality “tank-based” smart toilet or a bidet seat add-on.

The smart toilet is a remarkable piece of technology, but the tankless models are a demanding one. They represent a trade-off: in exchange for a minimalist aesthetic, you must provide maximum plumbing performance.