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Low-Flow Toilets: Are They Worth It?

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Bathrooms waste resources around the home, especially water – often, lots of it. While the faucets and showerheads are culprits, toilets are by far the main source of water use in the bathroom.

According to WaterSense, toilets account for nearly 30 percent of an average home’s indoor water consumption. More so, homes with older toilets use as much as 6 gallons per flush – hence, a major source of wasted water in many homes.

That’s why one of the easiest fixes for water consumption in the bathroom is to change out high-flowing faucets, showerheads, and toilets.

By reducing the water flow, you not only save on water bills but also create a more eco-friendly bathroom. In this article, we talk about low-flow toilets as a way to conserve water.

What Are Low-Flow Toilets?

Also known as low-flush toilets, low-flow toilets are designed to use less water than standard toilets to clear waste.

Generally speaking, older toilets use more water than newer ones. From this report, toilets made before 1982 used up to 5 to 7 liters for each flush. Between 1982 and 1993, toilets used 3.5 gallons of water per flush.

Later that 1994, toilets were made to flush with 1.6 liters of water. These days, 1.28-gallon high-efficiency flush toilets are common and some manufacturers have begun developing toilets with consumption levels as low as 0.8 gpf.   

NOTE: According to the US Environmental Protection Agency‘s WaterSense program, certified toilets meet the goal of using less than 1.6 US gallons per flush.

Therefore, if your toilet uses more than 1.6 gallons per flush, it will need to be replaced with a new fixture, and inspected, before a home is sold.

FAQ 1: Low-Flow Toilets Vs Regular-Flow Toilets

Apart from their water-saving feature, low-flow toilets have a larger flush valve than regular flow toilets. This means it can produce a better flush with much less water by getting the water into the bowl and down the drain more quickly.

Low-flow toilets unlike regular flow toilets have more water located near the front of the bowl, making it easier for waste to travel to the outlet since more of the bowl base is submerged in water.

NOTE: This reserve of fresh water also seals against sewer gases escaping into the home better than in regular flush toilets.

Additionally, the waste outlet in a regular-flow toilet is located near the back end of the toilet while it is located near the center of the bowl in a low-flow toilet, meaning that less water is used to carry waste away in the direction of the exit.

FAQ 2: How do you know if you have a low-flow toilet?

Given the wide variety of toilets in the market, it might be challenging to determine how much water a toilet uses simply by looking at it. However, here are a few quick techniques to figure out a toilet’s flush volume:

1. Check the label near the seat hinge. A modern toilet will have a mark that reads 1.6 gpf (gallons per flush) or 6.0 lpf (liters per flush).

Low-Flow Toilets: Are They Worth It?
Courtesy: City of Santacruz

If you don’t find such a symbol, look for a date stamp on the inside back wall of the tank or the bottom of the toilet tank’s lid.

The manufacturing date is usually stamped into the porcelain of toilets and based on the data shared above, you can estimate how much water the toilet uses.

2. Measure the water tank capacity. Here, turn off the water supply valve to the toilet then mark the factory set water line or mark the water level with a pencil if not visible.

Now, flush the toilet, and mark the reduced level before refilling the tank with a gallon container. Note how many gallons of water it takes to refill the toilet tank by noting the difference.

Remember to open the water supply valve when finished.

How to Choose a Low-Flow Toilet

Water conservation measures in the bathroom demand low-flow fixtures including the toilet. But with the variety in the market, you may be wondering how to choose the right low-flow toilet.

There are three basic categories of low-flow toilets:

a) Gravity-assisted toilets: for such a common design found in homes, these toilets use induced gravity to empty the toilet bowl.

Upon pulling the handle, water falls into the bowl producing a siphoning effect in the trapway at the base of the toilet that moves the water and waste through the pipe and into the septic tank or utility sewer pipes.

Following this gravity-induced removal of waste and water, a small gushing hose fills the tank with fresh water until a float stops the flow. There is also a tiny overflow tube to retain the water inside the tank and avoid overflow.

b) Pressure-assisted toilets include a small tank within the main tank to supply additional pressure that assists the force of gravity.

As water displaces air within the smaller sealed tank inside the larger tank, a larger force is generated to clear the waste. Because of this, flushing these toilets produces a loud whooshing sound characteristic of the air pressure being forced through the tank.

c) High-efficiency toilets, also known as dual-flush toilet that are more effective and use less water. In the dual flush system, one flush is designed for urine only, using even less water than the other designed for faeces.

If you are in the market for a new low-flow toilet, look out for these functional features to ensure you purchase the toilet best suited to meet your sustainability needs:

1. Install a WaterSense labeled toilet

Installing a toilet with the WaterSense label is a water-efficient option worth considering whether upgrading a bathroom, building on a new house, or simply replacing an old, leaking toilet that is wasting money and water.

These toilets use 1.28 gallons per flush or less while still providing equal or superior performance meaning the average family may save 20 to 60 percent on toilet water use.

2. Find out the model’s Maximum Performance (MaP) Score

If you can, find out your toilet’s MaP score, which demonstrates efficiency in removing solid waste. If it’s 800 or more, the toilet flushes very well with little or no problems to the consumer.

3. Go for a Taller Toilet Bowl

Due to its extra raising of the bowl height, a tall toilet gives a powerful flushing system that helps clear any clogged parts and blockages.

This convenient height also helps save you more than twice the water needed to flush a regular toilet because less water is used to empty the bowl.

4. Pick a Dual Flush

A dual flush is another important feature to consider when purchasing a new low-flow toilet.

With a dual flush, you can control how much water to use for each flush – clearing liquid waste from a toilet bowl uses less water than solid waste.

Hence, you can control your flushes to save water without compromising your toilet’s functionality.

Problems With Low-Flow Toilets & How to Fix Them

While low-flow toilets can help lower your water bill by reducing the amount of water used when flushing, they also attract some problems.

Below are some of the common problems with low-flow toilets and how to fix them:

1. A Clogged Toilet

Using less water makes it more likely to have the problem of a clogged toilet due to waste blockages. This is very likely, especially if you have low water pressure in your home.

With a clogged drain, the toilet gurgles or flushes poorly and you may notice sewer smells.

Other common signs of a clogged toilet include:

  • Water rising in the toilet bowl.
  • Having to hold the handle down to get a proper flush.
  • Slow flushes where the water in the bowl rises quickly, but falls slowly.
  • Sounds coming from other drains in the area when the toilet is flushed.
  • Bubbles coming from the trapway opening during the flush.

If a plunger doesn’t do anything to fix the clog, we recommend consulting a plumber for a drain cleaning.

Occasionally, force a large flush to clear any debris that may be sitting in the toilet’s waste stack and trap. Do this by pouring a large bucket of water into the system to trigger a manual flush.

However, if your toilet is clogged, use a plunger to unclog it before trying to force a flush through your low flush toilet as this will likely cause an overflow.

Plus, if you have a low-flow toilet, it’s critical to treat low water pressure at once to avoid such blockages. Have a professional plumber fix leaks and broken pipes, clear clogged rims, or fix the toilet flapper to curb low pressure in the toilet.

You can also lessen the likelihood of clogs by using less toilet paper and keeping your toilet clean and flushed after use. You should never flush things like menstrual pads and diapers down a low-flow toilet.

Another solution for a clogged low-flow toilet would be to use a pressure-assisted low-flow toilet instead of a gravity toilet due to its powerful flushing action that makes it clog less often.

This is especially helpful in older homes with dilapidated sewage lines that are subjected to frequent clogs, as the extra power of the flushing action can push waste past sticking points within the sewage line.


Pressure-assisted toilets can be especially noisy with all the whooshing involved with flushing. Make sure to listen to it first so you know it won’t be a nuisance in your home.

Read reviews! Pressure-assisted low-flow toilets are rather new on the scene, and some tend to break easily. Broken parts are more than annoying; replacing them constantly can create an abundance of plastic waste. The key is to research thoroughly before buying.

2. Costly Plumbing Modifications

Another potential con of having low-flow toilets is that they may require plumbing modifications which may get costly, especially if you live in an older home.

Even though a worthy investment, replacing an old, inefficient toilet model with a modern low-flow toilet demands a budget let alone its installation.

Plus, low-flow toilets either used pressure or gravity to carry waste to the outlet. Gravity toilets rely on water from the tank flowing down through the earth’s gravitational pull to empty the toilet bowl. 

Pressure-assisted toilets, on the other hand, utilize a secondary tank inside the main toilet tank to create additional air pressure to help generate a more powerful flush using less water. Therefore, they flush more waste at once and use less water.

If you have an older property with old toilets, this means that you may need to pay extra for a plumber to adapt your drainage system to accommodate a low-flow toilet.

3. Less Water To Adequately Clean the Bowl

Because low-flush toilets use less water per flush, sometimes, the amount of water used for each flush is insufficient to adequately empty and clean the bowl.

This forces the user to use two or more flushes(or even pour from a gallon container) to sufficiently clean the bowl, counteracting its intended water-saving goal.

To fix this issue, manufacturers are modifying the passageways to rigorously move a smaller amount of water around the bowl upon flushing.

Also, dual-low-flush toilets are another effective fix. By providing two flushing options—a full flush for solids (feces) and a half-flush for liquids (urine), this type of toilet conserves water.

More so, dual flush toilets employ a bigger trapway (the hole at the bottom of the bowl) and a wash-down flushing design to move waste down the drain.

This ensures less water is used per flush because the greater diameter trapway makes it simple for waste to exit the bowl.

Adding this to how this toilet uses half-flushes for liquid waste, the dual flush toilet design can save up to 68 percent more water than a standard low-flow toilet.

Are Low-Flow Toilets Worth It?

Low-Flow Toilets: Are They Worth It?

Yes, low-flow toilets are worth it because they help conserve water in the bathroom, lowering your water bills.

Just be sure to choose the right low-flow toilet and work with a licensed plumber to install one that’s right for your home.

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