In the pre-1970 period toilets were 6-12 gallons per flush. Then 5 gallons became standard, until 1992 when "low flush" toilets were the only kinds allowed to be manufactured in the United States. I have read plumbers making the rather unbelievable claim that modern 1.6 gallon toilets flush better than 6 gallon toilets. Is this just a plumber trying to justify his business or some kind of reality?

All I know is that I have a house built in 1999 and the toilets flush like crap to use a pun.

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    It depends on the type of toilet, I remember when my little brother was building his house a few years back he found toilets that would flush 36 or 39 golf balls I don't know if even one of those old time big tank toilets would flush that well recently I replaced a toilet in my house first one I have purchased in years. All the toilets used the same quantity of water or close but there were 3 or 4 levels of flush from in my words get er done. Down to probably will take 2 for number 2. – Ed Beal Nov 6 '18 at 17:52
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    Newer toilets use a different siphon design which increases the momentum of the flow without increasing the water volume, so it's certainly possible. Some work better than others, though. As-is, your question is broadly answerable as, "yes" – Hari Ganti Nov 6 '18 at 17:55

As always, government regulations come on fast, with the expectation thqt industry will turn around and comply promptly. Early on, the low-flow toilets were designed with one objective: save water to meet the looming regulations. Flushing properly was left by the wayside in their rush to meet the low-flow requirements.

As years went by, and low-flow became the norm, they got out the sharp pencil and really started iterating on the problem of getting them to flush well. In the interceding years, they've done very good work on that. I no longer notice flushing problems in modern low-flows. They've worked the kinks out.

It sounds like yours is an early "compliance model", I would shop for a new toilet. Read the reviews.

As for "better" that kind of engineering was never really done with the old toilets. They just did the job with an overwhelming mass of water, "throwing water at the problem", which isn't really engineering, is it.

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