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Thread: Toto, Gmax vs. Power Gravity + 1.6gpf?

  1. #1

    Default Toto, Gmax vs. Power Gravity + 1.6gpf?

    Does anyone have a technical discussion about the differences between these two items. How would your rate each against each other and which would you get. I read some info. on the web but could not seperate the two? I just installed a Supreme (with pwr gravity) and the bowl above the water does not clean well because the water just dribbles down the sides of the bowl, rather than swirl around like the old one. Of course, the 1.6gal is so much less water that you pay the price of not getting the bowl a little cleaner.

    Also computed the volume of water that is flushed. The tank filled to the water line measured 377 cu in (1cu in = .004329gal) = 1.63gal of water in the tank (not accounting for valves+flapper). After a flush, the height of the water dropped 2.5in which computes to only 0.82gal being emptied from the tank into the bowl. Now I know that water is still entering through the tube into the bowl while the tank fills up. So the question is, how is the 1.6g/flush computed. Does it mean 1.6g actually goes down the drain?

  2. #2
    Forum Admin, Expert Plumber Terry's Avatar
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    G-Max has higher water in the tank, so it uses the red flapper that drops quicker.
    Power Gravity has the lower level in the tank, uses the blue flapper that stays up longer.

    The water measured, is the total of the water that leaves the toilet during a flush. Even if you see the tank drop, you still can't count fast enough, to account for the immediate filling of the tank and bowl by the fill valve. It fills near the bottom of the tank, and from the black tube leading into the overflow.

    And that's the way "all" 1.6 gallon toilets work.
    Even the old 3.5's don't use much water for the flush itself, that's why some plug easier than the new ones. The old toilets tend to overfill the bowl, long after the flush has happened.

    Last edited by Terry; 06-16-2009 at 12:58 PM.

  3. #3


    Thanks Terry,
    Are U saying that PGravity only is in low height tanks? I see that the ms853113 Ultimate uses PGravity but has a high tank. Does that mean the the water in it is low, like my Supreme? The ms853113s UltraMax looks the same but has the G-max. Are the water levels between the two different?
    The higher water in the tank should flush with a little more force because the water head is a little higher

    I measured the the 2.5in drop in height of the water before the flapper shut. Thus approx. .8gal left the tank. So the rest of the .8gal is what went down into the bowl by the black tube and when I flush, the tank water and the bowl water =1.6gpf?

    I saw a diagram in a drake or supreme forum that showed the siphon effects of the Toto compared to standard. Was it close to correct? Is there alredy water in the 2 1/16 drain down to the 2nd water trap. Or, is the drain empty till the flush occurs with only water sitting in the bowl? I thought a real siphon effect requires the water to be continous, like when I drain my fish tanks with a hose?

  4. #4


    Just a follow-up to my previous post. We added two TOTO Drakes to our upstairs bathrooms. When comparing the Gmax vs. the PGravity of our Supreme....the Gmax has a more powerful flush. The water in the tank is higher than the Supreme. The Plumber said he saw a TOTO demo that flushed a roll of quarters down.

    The Drake is a little more nosier, and makes a "plop" sound when the flapper closes and hits the base, but it flushes. All three take about 20sec to fill, compared to a 1min 10sec with the original 3.5 gal version. The one elongated version also has the sani-bowl finish. With the new 1/4 turn valves and flex line, plus new wax seals and anchor bolts, I'm good for a many years. I was a little worried that when they took the old ones off, that I would have lots of damage to the wood floor or ring. No problem with any.....really lucky. Nice to get them all re-done...something you think about for years and not do anything about because it's messy and it "still work" but when it is done, what a relief to not have to worry about this. I recommend a new toilet.


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