Low-flow toilets versus "getting it down the line"

Old 10-28-19, 08:17 AM
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Low-flow toilets versus "getting it down the line"

The one and only concern I have about low-flush-volume toilets in general is whether that low flow might, shall we say, inhibit the movement (pun intended) of the solid waste down the sewer line from our house to the street.

I know that the slope of a sewer line in a home (and, for that matter, those under streets) is carefully set so that the liquid part of a flush/flow does not run too fast and leave the solids behind, but I don't know if or how the volume of water per flush enters into the equation for setting ideal slope.

Presently we have an old style toilet in a 40-year-old home that probably uses 4 or even 5 gallons per flush. If whatever's in the bowl doesn't plug up the toilet right off the bat, that large volume of water must push/flush everything down the pipe very well.

The toilet we're considering uses only 1.28 gallons per flush. I'd be tempted to flush twice, just to be on the safe side, especially after "the big one".

Do you have any information that might be helpful on this particular issue? I'd be very interested to hear from those who already have had low-flow toilets for a few years. Have any of you had the sewer line get plugged because of what you suspect to be that low flow?

Old 10-28-19, 08:38 AM
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Low volume toilets

There are plumbers on the site that can give you a more definitive answer, but this is what I know from my own experience.
When low volume (1.6 GPF) were first mandated by code in the early 90's I installed two new toilets. They were problematic with lots of 2nd and 3rd flushes to clear the bowl. Low volume toilets had a very bad rep for a while. That was quite a few years ago. Since then I have replaced my toilets with newer models during a reno. I have never had a problem with the newer model; toilets.

Just my opinion but I think at the start many toilet manufacturers used the same bowl design and simply limited the volume of flush water. I don't think that is the case any longer.
Old 10-28-19, 08:56 AM
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I have not heard of a sewer line plug due to a low flush toilet.
Remember, it is not only the toilet going out the line you have the sinks, dishwasher, clothes washer etc etc so there is still a lot of water flushing (pun intended) it.

Just research the toilet for any complaints.
In the early days, many of them were crap (pun intended again). Things are much better now though like anything else there are bad ( avoided a natural pun on purpose) ones out there.
Old 10-28-19, 09:55 AM
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I have a number of rental properties and none have ever had a clog I consider caused by a low flow toilet. Many of the houses were built long before low flow toilets were invented. Over the years I've gotten most switched out to modern low flow toilets and there have been no problems. In some cases I would say it's even helped. If there is a partial clog or obstruction already in a drain line the smaller volume flush can slowly work through the restriction without causing a backup as often as a high volume flush.
Old 10-28-19, 02:15 PM
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Thanks for the great replies, guys! I really appreciate it.

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