I need a toilet for the bathroom off a master bedroom that's being built in my house.

Once when my Mother had a plumber in to fix something else, he told her to hang on to her old fashioned toilet as long as she could - plumbers have far more problems and calls about the new high efficiency toilets.

I see that Home Depot and Lowes primarily have 1.23 Gallons per Flush (GPF) toilets in stock, but you can also get 1.6 GPF toilets.

According to Consumer's Reports, more water sometimes (but not always) means better flushing. And all of their best rated toilets use 1.6 GPF.

Should I go for the 1.6 GPF toilet to avoid problems and having to clean the toilet as often? Or have the 1.28 GPF toilets improved enough to use one of those instead?

I live in Minnesota where water usage isn't as big of an issue as it is in California.

  • 1
    How much are you willing to spend? Pressurized low-flow toilets work very well.
    – Matthew
    Commented Nov 24, 2012 at 0:14
  • I've never had a problem, even in the morning after Beer and Wing night. Commented Nov 24, 2012 at 14:39
  • We commonly use 1.23GPF/0.8GPF(4.5L/3L) dual flush toilets which have adjustable outlet valves for using on retro fit toilet pans. The only problem I've come across is using a new low water cistern on a old toilet pan as the design of the waste flow is diffrent in new toilets to allow for the low water usage.
    – UNECS
    Commented Nov 25, 2012 at 1:33
  • Thanks for all the suggestions. While I was shopping in Lowes I ran into a plumber, who said that the amount of water and the size of flush valve determine how likely the toilet is to clog. He very highly recomended the American Standard Champion 4 (1.6 GPF). They were on sale for $230. He said that the 4" diameter flush valve was bigger than any of the others there, and was the key to preventing clogs. lowes.com/…
    – Curt
    Commented Dec 3, 2012 at 21:57

7 Answers 7


More GPF is usually better for disposing waste, but it's less environment friendly. If you don't mind that little bit of extra water and sewage costs, go for the toilet that's more comfortable for you.

Also, it's always a good idea to get a tank with dual flushing system (I don't know if you have any others, I'm not from the USA).

  • 1
    There's no free lunch. Somebody else mentioned pressurized low-water toilets, though, and those really can work well. I've seen models that would suck down four or five ping pong balls. Commented Dec 21, 2014 at 21:45

Some of the low volume toilets manage to flush very quickly because of newer designs. Some of it has to do with coatings on the bowl, and the pathways inside of the toilet. But one change that makes a large difference is a larger flapper and opening that allows the water to drain much faster (the only downside is that you'll need special replacement parts in the future).

The last time I was shopping for toilets, they had a rating of how powerful the flush was in each toilet, which is much more useful than the gallons per flush. My newest toilet flushes much better than any of the older toilets, while using much less water.


TLDR: It's the shape of the bowl and not the volume of water that determines clogging.

There are 3 types of flushing toilet pans:

Siphonic (washout)

Deep water

The siphonic toilet has a higher water level and uses a siphoning wash to "suck" out excrement. If you're in North America, this is probably what you're using. It has a narrower flow and is prone to clogging.

"European" (wash down)

Low water

The wash down has a shallow water level with a wide flow. It used the fast moving water to "push" out the excrement. If you're in a "civilised" country, you're probably using this and wondering how anyone could clog a toilet.


Don't use this. Don't even look up information about it... it's like a nightmare.

Personal recommendation

I live in a "civilised" country where "wash down" is the standard - I'm a big fat man and I... use toilets to their full extent, if you know what I mean. But I have NEVER clogged a wash down toilet and I didn't understand how anyone could clog a toilet until I travelled to America, then I understood how easy it is. If you want a toilet that doesn't clog, get a wash down and not a siphoning pan.

  • 2
    Sorry, but those warnings piqued my curiosity. Reminds me of a Volkswagen mechanic who went through the German Volkswagen school. The introductory class started out with, "There's the right way, there's the wrong way and then there's the German way. You're going to learn how to do it the German way." However, the German way when explained often had a really good, expedient or long lasting repair as a result, unlike this toilet. Commented Aug 30, 2013 at 14:27

1.6 GPF can be adjusted to save water such as adjusting the water level but 1.28 GPF has no option to carry more water. Therefore, never buy 1.28 GPF but 1.6.

  • It really depends on the design of the toilet. some of the low flow models can flush 26 golf balls with 1 flush but there is no standard just purchasing a higher flush may have worse results based on the design.
    – Ed Beal
    Commented Jan 24, 2017 at 13:58
  • You might be able to design a 1.28 GPF to do a good job of getting solid waste out of the toilet. But then it needs to be washed down the drain pipe. The more water that goes with the flush, the better a job it will do moving the waste after it leaves the toilet.
    – fixer1234
    Commented Sep 8, 2018 at 22:13

A plumber told me the more water the better as far as toilet reliability. My son-in-law told me of some people who bought .8 gpf toilets and there house sewer line clogged due to not enough water to move solid waste out into the sewer system. They had to instal toilets using more water again. I bought an American Standard Titan (Menards version of the Champion 4) using 1.6 gpf. A second function of water when flushing is to move the waste down the sewer pipe. Older homes often have cast iron pipes that offer more resistance to waste flow. American Standard has designed the toilet trapway to be 2 3/8" in diameter, the widest I have seen. Some toilet trapways are only 2" in diameter. The extra diameter of the trapway can carry more waste. The 4 in the Champion 4 means 4" diameter toilet tank drain into the toilet bowl. Additionally the toilet uses a piston valve so water rushes in from all sides much like the Kohler design. In over a years time I have not had significant plugging issues and I use a lot of toilet paper. The few times the toilet has clogged no plunging was necessary. I simply reflush and the toilet cleared itself. My advice is to get the most water per flush and to go with a 4 inch flush valve made of a piston to maximize water flow. Newer homes have pvc pipes and plumbers can lay out the piping for lower water use toilets. Then you can look into a 1.28 gpf toilet but be aware the lower water use can result in less "cleaning" of the bowel.


I always think that I can’t do much with the toilet, but I can with the design of the sewage system.

I like the sewer pipe installed with as much slope as possible, (up to a point...anything over 2” per foot is unnecessary and could cause the solids to separate from the liquids).

I also like the toilet “ahead” of the tub and shower in the sewer drain system. That way, when the tub is drained, it will “wash” the pipe clean.

However, (as everyone has mentioned) the more water in the flushing cycle, the better.


I installed a Home Depot Glacier Bay 1.28 gal toilet in my vacation rental and have had to have it professionally unclogged 3 times in 12 months. If you hit the flush valve handle quickly and don't hold it down for a few seconds, the flapper closes before the tank has a chance to drain it's 1.28 gallons. I'm going to change out the stock flapper assembly (which leaves 3.75" of water in the bottom of the take when you do hold it down!) with an after market model that will make it a 1.6 toilet again. Also, don't ever buy a toilet with the push buttons on the top lid. The side flush handle has worked well for 100 years. Putting it in the lid is ridiculous!

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