Green Home Remodeling: Low-Flow or Dual Flush Toilets?

Published on October 5th, 2010 | by

If you live in an older home or apartment, the toilet in your bathroom uses between three to four gallons of water each time you flush.  In fact, your toilet is the “largest daily user of water” in your home.  Some water conservationists respond by only flushing down bowel movements and posting signs for visitors reading: “If it’s yellow let it mellow; if it’s brown flush it down;” however, the smell and sight of a urine filled toilet is not pleasant.   New installations and remodeling projects are left with two flushing options:  low-flow toilet or dual flush toilet.

Photo by NatalieMaynor
Dual flush or low-flow?
Dual flush or low-flow?

Toilets manufactured after 1992 are mandated by US federal law to “to meet or beat” efficiency standards of 1.6 gallon per flush.  Once considered the “bane of the bathroom“, early low-flow toilets had a bad reputation for requiring multiple flushes to get solids down, thus frustrating consumers and not conserving water in the process.  Newer models are much more efficient, and many allow consumers to adjust the water output to the perfect amount for their personal use.  Instead of relying on gravity, like older toilets, new low-flow toilets may use pressurized air.

Dual flush toilets are different than low-flow toilets in that they give you two options for flushing.  DIY Network explains, “The world’s driest continent — Australia — brings us dual-flush toilets, which give you a choice: push one button for flushing liquid waste (.8 gallons of water) and another for solid waste (1.6 gallons).”  DIY eco-friendly dual flush toilet retrofit kits are available, or you can buy a toilet that is already equipped with this option.

We recently put an addition on our house, and both of our bathrooms feature each kind of water conserving toilet described above.  Our low-flow toilet was very expensive. At first we hated it, as it used such little water that the toilet bowl was always dirty.  We then discovered the water adjustment, and we have had no more problems.

Our dual flush toilet was a one-fifth the cost of the low-flow toilet, as we were able to buy it at a large warehouse store versus a local plumbing supply shop.  Although it is better to shop local, sometimes you have to save money when doing home repairs. We are happy with our dual flush toilet, but in the middle of the night, I just press whatever button without paying attention. I suppose as I become more familiar with the toilet, I’ll remember which button to use.

Of course, you can avoid water consumption all together by installing a composting toilet, but low-flow and dual flush toilets are more acceptable to many people.  ABCs of Toilets reports that if everyone switched to water-efficient fixtures, we could reduce water consumption by 30%.  In these times of pressure on dwindling fresh water supplies and reservoirs dropping to 40% of capacity, we all should be using water conserving toilets.


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8 comments

  • Great article and thanks. We discovered another and much less expensive option of the retrofit kit called the Dual Flush Retrofit Kit. At $25 vs $100 for the one linked in the article, it is worth a look. I’ve installed four myself in 1.6-gallon two-piece toilets and they work perfectly. Check em out!

  • Dual-flush is just one type of high efficiency toilet (HET) available today. An HET is a toilet that uses 1.28 gallons per flush or less–a 20% reduction from standard toilets. Studies show that dual flush HETs and single flush 1.28 gpf toilets consume about the same amount of water. Whether you prefer dual or single flush, you are correct that replacing an old, 3.5 gpf toilet with a new HET is a great way to save water.

    However, I disagree with your recommendation about the retrofit kits. Toilets are designed to comply with various standards, and changing the flush volume of an existing toilet may make the toilet perform poorly. The best way to ensure water savings and good performance is to purchase a toilet that was designed to be an HET.

  • I have an old house and would like to make a corner ecoroom for my bedroom. I now have a bay window and grills on both sides so I plan to remove the grills and the walls to open up to a wraparound lanai nwith trellisses. Can anyone suggest how to replace the grills with something more aesthetic to providfe security from break-ins and allow cross ventilation and also suggets materials of construction as wood is eaten by termites and also how to prevent mosquitoes from entering in as screens obstruct windflow. I also would like to use a water catchment for the roof so that rain water can be used for toilets and garden water. Pls share your eco-thoughts.

  • I have installed the MJSI HydroRight dual flush converter and couldn’t be happier. The installation process was easier than anything I’ve done before. No tools required! Within minutes, we had a dual flush toilet, conserving water. Thanks MJSI!

  • […] Dual Flush Toilets: These toilets give you the option of flushing for liquid waste or solid waste. What does this mean? Well, naturally, it should take less water to flush liquid waste than to flush solid waste, so when you’ve only got a little liquid to flush, you can choose your flush option for that. When you think about how many times you actually use the toilet for solid waste, this option reduces your water consumption by over half with each flush. […]

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