This article details toilet water use per flush (based on age & efficiency of the toilet).  At the end of the article we discuss the 3 toilet heights available today. 

• Toilet are; Low-Efficiency (3-5 gallons per flush – GPF), Standard-Efficiency (1.6 GPF), High-Efficiency (1.28 GPF) and Ultra-High Efficiency (0.8 GPF).

• Toilet heights are; Standard Height (15″ high); Comfort / Chair Height (17-19″ high) and Convenience Height (20 -22″ high). 

Al’s Plumbing, Heating & A/C in Plano, Texas provides maintenance & repairs for all brands of Central A/C, Gas & Electric Furnace, and Heat Pumps.  Additionally we sell and install new HVAC Systems from American Standard (same company as Trane),  Ameristar (same company as American Standard) and Coleman HVAC (same company as York HVAC).

Al’s also provides full service plumbing maintenance, repairs and replacements for every plumbing component in your home.  Al’s sells and installs Rheem Professional Series gas & electric water heaters, and tankless water heaters.  Al’s is near your home in Plano, TX; Allen, TX; and Frisco, TX.  We service all homes in southern Collin and Denton Counties with no travel charges.

Call Al’s today to discuss any concerns or problems you have with your HVAC System or Plumbing.  We will arrange an appointment at your convenience and offer 24/7 Emergency Service.

Interested in making your bathroom appear larger?  We have a detailed article with 50+ ways to make a small bathroom appear larger:

50+ Ways To Make A Bathroom Appear Larger

Toilet Age Determines

How Water It Uses

With Older Toilets, You Can Typically See The Outside Contours Of The Trapway (as show)

Image Source: ShutterStock

If you’re in the market for a replacement toilet, there is a dizzying array of choices.  For those of in Texas & California, the choices are more limited.  These two states do not allow 1.6 Gallons Per Flush (GPF).  Both states require High-Efficiency Toilets (HET) which use no more than 1.28 GPF.  In Texas, there are certain models of Dual-Flush Toilets available.  Many of these have 1.1 GPF (for only liquids) Plus a 1.6 GPF (for solids).

Currently there is one toilet described as Ultra-High Efficiency available.  It uses 0.8 GPF.  It is the Niagara (brand) Stealth (model) Toilet (Model 77001WHCO1).  We discuss this specific toilet later in this article. 

Siphonic Toilet Design  

• This was the common toilet design BEFORE 1992.
• A Siphonic Toilet has a long & narrow trapway —  typically 2″ in diameter is common.

• These are considered low-efficiency toilets.
• These toilets used 3 — 7 Gallons Per Flush (GPF) — (depending when toilet was made).  An average = 3.5 GPF
• This toilet PULLS waste from the toilet.
• The toilet-bowl water level is higher.
• The toilet-bowl water has a larger surface area.
• Upon flushing, the water in the bowl rises before dropping.
• This is because water is flowing out of the tank faster than it can exit the bowl.  This is due to the smaller trapway (2″ versus 4″).

Washdown Toilet Designs 

• This is the common toilet design AFTER 1994 — when The Energy Policy Act required toilets use no more than 1.6 gallons per flush (GPF).
• A Washdown Toilet has a shorter trapway with a larger diameter — typically 4 inches in diameter.

• These are Standard-Efficiency toilets.
• These toilets use 1.6 GPF or less.
• NOTE: Texas requires 1.28 GPF toilets.  Texas House Bill 2667 was signed into law in 2009.
• This toilet PUSHES waste from the toilet.
• Advances in toilet design allow WaterSense HETs to save water without loss of flushing power.  Many HETs actually perform better than today’s standard toilets.
• The toilet-bowl water level is lower.
• The toilet-bowl water has smaller surface area.
• Upon flushing, the water in the bowl drops immediately upon flushing.
• This is due to the larger trapway (4″ versus 2″).

Click Here To See A Side View Diagram Of A Sophonic Versus A Washdown Toilet: Side View Diagram — Siphonic & Washdown Toilet

Click Here To See A Sophonic Versus A Washdown Toilet Flush In Action:  Siphonic & Washdown Toilets During Flush

Click Here To See An Animated Side View Of A Sophonic Versus A Washdown Toilet: Siphonic & Washdown Toilet Animation (Side View)

• A WaterSense Labeled toilet is called an High-Efficiency Toilets (HET) —  it uses 1.28 GPF or less.
• These are considered High-Efficiency Toilets (HET).
• NOTE: Texas requires HEF for all installations, both new construction and replacement toilets in existing home.
• To earn the Water Sense label, the toilet must use 1.28 GPF or less.
• Some models use as little as 0.8 (8/10) GPF.
• The WasterSense logo helps to quickly identify 1.28 GPF toilet.

• These toilets have a larger diameter flush-valve than 1.6 GPF models.
• Their Canister Flush-valve diameter is 3 — 3.25 inches.  A Flapper Flush-Valve diameter is as small as 2 inches.
• 1.6 GPF or higher GPF toilets have a flapper flush-valve.
• The larger canister flush-valve delivers water to the bowl faster.  This creates greater flushing force.
• This is how a 1.28 GPF toilet can deliver similar or superior flushing than a 1.6 GPF toilet.

The WaterSense Label Is Shown Beside This Toilet

Click On Image To; View Product, See Details, or Purchase From Amazon.com

Image Source: Amazon.com

Click Here To See A Photo Of A Flush-Valve With Flapper (flapper is red):  Flush Valve With Toilet Flapper

Click Here To See A Photo Of A Flush-Valve With Canister (also called piston): Flush Valve With Cannister / Piston

When This Article Was Written, The Niagara (brand) Stealth (model) Toilet (Model # 77001WHCO1)

Is The Lowest Water Use Toilet Available  

• It uses 0.8 GPF (8/10 of 1 gallon).  This is half the water usage of a today’s standard-efficiency / 1.6 GPF toilet.   

• This is considered an Ultra High-Efficiency Toilet (U-HET).

The Manufacturer’s Explanation Of Why & How This Toilet Uses So Little Water: 

• “Our Vacuum-Assist Technology Delivers a Powerful Flush.
• Before Flush: As water fills the tank, air is pushed into the air-transfer tube.
• This pressurizes the trapway and primes the toilet for a powerful and quiet flush.
• When flushed, water leaves the air transfer tube.  This pulls air from the trapway upward through the air-transfer tube.
• This creates a vacuum-assisted pull that accelerates the force of the water & waste flowing through the trapway.
• Once the flush is complete, the system refills and is primed for the next flush.”

Click Here To See The Niagra U-HET flush in action (skip to minute 3.0 to see actual flush):  Niagra U-HET Toilet Flush

Niagara Brand Toilet (Model 77001WHCO1) uses only 0.8 GPF (8/10 of 1 gallon).

Click On Image To; View Product, See Details, or Purchase From Amazon.com

Image Source: Amazon.com

At the time this article was written, Amazon shows buyers of this specific brand & model of toilet gave it a rating of 4.6 (out of 5.0) — with just over 1,000 reviews.

NOTE: Texas Does Not Allow Standard-Efficiency / 1.6 GPF toilets.   Texas does allow Dual-Flush toilets that use 1.6 GPF as their full-flush option. 

Dual Flush Toilets

The Dual-Flush Toilet Shown Just Above Uses 1.1 Or 1.6 Gallons Per Flush (GPF)

Click On Image To; View Product, See Details, or Purchase From Amazon.com

Image Source: Amazon.com

Your Current 1.6 GPF Toilet Can Be Upgraded To A Dual-Flush With A Toilet Repair Kit

With Dual-Flush Converter 

Click On Image To; View Product, See Details, or Purchase From Amazon.com

Image Source: Amazon.com

NOTES: 

• This product is for 1.6 GPF toilets.
• It does not work with 1.28 GPF toilets.
• It does not work with older toilets (built before 1982).

Toilets Are Available In 3 Different Heights

NOTE: Regardless Of Toilet Height — An Elongated Bowel Is 2″ Longer Tan A Round  Bowls.

Addressing This Issue, Toilets Are Offered in 3 Toilet Heights. 

• Standard Height: 15 inches from the floor (including seat).

• Chair Height: 17-19″ high (including seat).

• Convenience Height: 20″ high (including seat).

• Note: Toilet height may vary by toilet brand.

• A standard height toilet around 15 inches from the floor (including the toilet seat).
• Those who are tall, elderly, or have mobility issues may find a 15″ height toilet too low.
• This height may make sitting down & getting up needlessly difficult.

Standard Height Toilet Shown.  Toilet Seat Height = 15″ from floor.

Click On Image To; View Product, See Details, or Purchase From Amazon.com

A Comfort Height (also called Chair Height) Toilet is 17 — 19 inches from floor to the top of the seat (height may vary by toilet brand).  This is similar to the height of a chair. The height of a standard toilet is 15 inches from floor to seat (may vary by toilet brand).

Click On Image To; View Product, See Details, or Purchase From Amazon.com

Comfort Height Toilet Shown Just Above.  Toilet Seat Height =  17.5 Inches.

NOTE: Comfort Height Toilets Bowl Seat Height Is The Same As A Standard chair.

A Convenience Height Toilet Is Taller Than Comfort Height

A Convenience Height Toilet is 20 or more inches from floor to the top of the seat (height may vary by toilet brand).

Click On Image To; View Product, See Details, or Purchase From Amazon.com

Convenient Height Toilet Shown Just Above:  Toilet Seat Height = 21 Inches. 

Click Here To See A Side View Of The Toilet Height, In A Side By Side Comparison: Photo Of Standard And Convenience Height Toilets

• This article discussed toilets with Low-Efficiency (3-5 gallons per flush – GPF), Standard-Efficiency (1.6 GPF), High-Efficiency (1.28 GPF) and Ultra-High Efficiency (0.8 GPF).

• Also discussed were the 3 Toilet Heights available; Standard Height (15″ high); Comfort / Chair Height (17-19″ high) and Convenience Height (20 -22″ high). 

Al’s Plumbing, Heating & A/C in Plano, Texas provides maintenance & repairs for all brands of Central A/C, Gas & Electric Furnace, and Heat Pumps.  Additionally we sell and install new HVAC Systems from American Standard (same company as Trane),  Ameristar (same company as American Standard) and Coleman HVAC (same company as York HVAC).

Al’s also provides full service plumbing maintenance, repairs and replacements for every plumbing component in your home.  Al’s sells and installs Rheem Professional Series gas & electric water heaters, and tankless water heaters.  Al’s is near your home in Wylie, TX; Rowlette, TX; and Murphy, TX.  We service all homes in southern Collin and Denton Counties with no travel charges.

Call Al’s today to discuss any concerns or problems you have with your HVAC System or Plumbing.  We will arrange an appointment at your convenience and offer 24/7 Emergency Service.