Low-Flush / Dual-Flush Toilets

Low-flush toilets – 6 litres or less per flush –often cost $100-$250, minus any municipal rebate. Replacing old, inefficient toilets can reduce your water and sewer bills by more than $100 a year, often resulting in a payback of less than two years.	Moderate effort to research and install low-flush toilets.	Replacing old toilets with low-flush models can reduce annual household water consumption by some 80,000 litres of water and cut greenhouse gas emissions by more than 100 kilograms.

In the average Alberta home, some 30 per cent of indoor water use is devoted to flushing toilets. All too often, more than half that water is needlessly flushed down the drain. Considering water is perhaps our most precious resource, it makes sense to replace old, wasteful toilets with new, efficient models that will save homeowners water and money, plus reduce their greenhouse gas emissions.

Why should I replace my old toilets?

Older toilets waste a huge amount of water. If your toilets were manufactured before the early 1990s, they likely use over 20 litres per flush – more if they leak. On a per person basis, that can add up to a bathtub of water per day and, over a year, require more than 35,000 litres of clean, fresh water to dispose of just 650 litres of body waste. Toilets sold in Canada after the early 1990s typically use 13 litres per flush and can still be purchased, even though six-litre models have been available for a number of years. So a family of four with older-style toilets – averaging 16.5 litres per flush, with each person flushing five times a day – is using nearly 80,000 litres of water per year more than a family with six-litre models. Making the switch to low-flush toilets could also save you more than $100 a year in water and sewage costs, if you are on a water meter.

Are there any other impacts from this excess water use?

Yes. It takes considerable amounts of emissions-producing energy – to say nothing of chemicals – to treat all this water, both at water treatment and sewage treatment plants. By reducing this unnecessary water use, we can also help delay or avoid the need to expand municipal water and sewage treatment plants. Of course, the impacts of climate change on glaciers and snowpacks in Alberta make it increasingly imperative to conserve our precious water supplies.

How can I determine how much water my toilets use?

The age of your toilet should give you a rough idea of its water use per flush (see the question above). For more precise information, look for the flush volume, often printed on the inside of the tank, back of the bowl, on the flush valve or on a tank label. You can also calculate the rough flush volume by multiplying the tank’s length by its width by its depth, all in centimetres. For example, 33 cm X 19 cm X 22 cm = 13,794 cubic centimetres, or 13.794 cubic litres.

How much water do modern, efficient toilets use?

The amount, per flush, keeps going down as new technologies are improved. The standard ultra-low-flush toilet (ULFT) uses six litres, or less, of water per flush. Increasingly popular are dual-flush toilets, which have a three-litre button for liquids and a six-litre button for solids; newer models use as little as 4.8 or fewer litres per flush. Dual-flush models are part of an emerging category known as high-efficiency toilets (HET), which must have an average flow of at least 20 per cent less than a conventional ULFT model – they typically range between 1.6 and 4.8 litres per flush. There are now more than 100 models of HETs offered by some 21 manufacturers. A family of four that switches from 20-litre to 4.5-litre HET toilets would save more than 110,000 litres of water per year.

Note: A growing number of Alberta municipalities now require that for all new housing construction and for renovations requiring a plumbing permit, new toilets must use no more than six litres per flush.

Don't these low-volume toilets tend to have problems like clogged drains and the need to double flush?

Early generations of low-flush toilets did have some performance problems. They have since been reengineered to the point where they typically perform better than conventional gravity-fed toilets. For example, a standard, gravity-fed ULFT now has a redesigned bowl to enhance its siphoning action, which pulls water out of the bowl. And HETs – some of which use a pressure-assisted mechanism to force waste down the trap –often outperform both ULFTs and conventional toilets. A wide range of new toilet models are regularly tested on their ability to remove solids in a single flush. For the latest performance report, click here.

Note: All toilets can experience problems when drain lines are degraded or damaged by such things as root intrusion, solids buildup and sags or breaks. Residential buildings with long drain-line runs can also pose problems.

How much do low-flush toilets cost?

Many low-flush toilets can now be purchased for $100 to $250. Some makes and models, especially those with high-end finishes, can cost hundreds of dollars more.

Can I retrofit my old toilet so it uses less water?

Yes, but retrofits should be considered short-term measures that will, at best, save a few litres of water per flush and may not perform consistently. The simplest remedy is to place or suspend a water-displacement device – such as a sealed bag or bottle full of water – in the back of the tank; don’t use a brick, which can disintegrate and interfere with the flushing action. More sophisticated solutions, often available at hardware and plumbing stores, include early-closure (adjustable flapper) devices and water-retention mechanisms such as toilet dams.

What can I do to check for water leaks?

Older toilets tend to leak, to the point where they can waste a bathtub full of water every day. To check for water leaks, put a few drops of food colour into the toilet tank and wait a few minutes. If the colouring appears in the bowl, you have a leak. Worn flapper valves and water-logged floats are relatively easy to replace; other problems may be somewhat more complicated to fix.

Do I need a plumber to install a new, efficient toilet?

If you are proficient at do-it-yourself home renovations, you may be able to replace it on your own. The task, however, can be complicated by a rotted or uneven sub-floor or by corroded connecting pipes.

What should I do with my old toilet once I've removed it?

Avoid the temptation to sell it or give it away. The whole idea is to get rid of these water guzzlers. If you use a plumber, ask if he or she will remove it. Otherwise, take it to your local landfill for disposal. At some landfills, old toilets are crushed with concrete into a reusable aggregate product.