Ok take this from a girl who knows her toilets and her plumbing being as I live in an 1890s home with twelve bathrooms. DO NOT DO NOT DON'T EVER buy low flush toilets for your period home.

The cast iron systems in our home demand a high volume flush. With low volume you will be constantly dealing with clogs unless you spend a fortune (and love loud noises) on vacumn assisted toilets. I have three pre-1920s toilets here and they take anything without issues. The balance are modern and inexpensive. You need to double flush regularly and I am constantly dealing with clogs over simple stuff. Each toilet has a jar of fabric softener on the back to assist with ummmm soft matter break down (you know what I mean?) and god forbid you use more than three squares....

Honestly, dh and I just had this discussion earlier in the week. We will be replacing the nines"non antique" toilets with antiques. We can easily see the difference being as we use both the antique ones and the new ones daily. The cheap ones suck! Actually quite the opposite.....don't go cheap...you will regret it!

By the way....I have two toto toilets in my 1980s remodeled townhouse. They don't hold a candle to the antique pillbox toilets in the old house. Same amount of money (couple grand) for each...and the old one out preforms the fancy new stuff easily! That said, dh says I. The house with toto's that the reproduction pillbox from max the antique plumber (online) still out preforms the toto's. If I couldn't find antiques I'd buy more of those.

essdana, It all depends (as you suggested) on the configuration of the pipes, not the age of the house. Our house is 95 years old, and 13 months ago in our downstairs powder room we replaced a 3.5 gallon per flush Eljer (always worked perfectly) with a 1.28 gallons per flush Toto Vespin II (flushes every bit as thoroughly, but refills much faster after a flush). Our reason for the swap was that the Eljer had a round bowl, and we wanted to fit an elongated shape advanced toilet seat (Inax Clessence) -- which we have not yet done, but soon, soon, soon (we hope; the electrician's charge just to put in one new 110 volt wall outlet for the advanced toilet seat ran about $400 over budget and well beyond reasonable, which forced us to delay until the bank account catches up).

In general, I would be more worried (not that it is likely to happen these days) swapping a high flow toilet for a low-flow one in a house with older plumbing. The more flow, the more there is to back up if restrictions in the old pipes are not up to passing the rate of flow of the effluent.

I am a recently retired master plumber and in all of my 35 years in the trade I don't recall reading or hearing so much mis-information at one sitting.

First of all, DO NOT equate the price tag of a toilet with its efficiency. I have two American Standard "All in One" kits in my house, which come as a complete set, tank, bowl, seat, wax ring and new mount bolts, all for the outrageous sum of $99 and I can assure you, if you flush my toilets while your seated you better hang on or you may go down the drain too.

The problem with retrofitting low flow toilets in vintage homes IS NOT the toilet.

To understand the problem we must first understand a basic premis on how the drain pipes function.

In all cases drain lines are sized so that when they are handling the full discharge load from the fixture a horizontal pipe will be 1/2 full. In this manner the depth of the liquid is sufficient to suspend and carry any solid particulates in the waste while still allowing the upper half of the pipe for the free movement of vent air.

Originally toilets discharged 5gal per flush and they determined that they needed a 4" line. In the late 70's or early 80's the code standards were changed and toilets were reduced to 3.5gal/flush and the old 4" lines continued to work fine, but in the late 80's they reduced the water to 1.6gal/flush. While the toilets all worked fine they began having serious complaints from customers about lines continually clogging. Most ppl automatically assumed the problem was in the fixture but such is not the case. When a 1.6gpf toilet discharges into a 4" line, the level of liquid in the line is no longer sufficient to effectively convey heavy solid particulates, thus the solids rub against the bottom of the pipe slowing their velocity, while the liquids continue to flow around them. In the course of time, and in this case generally rather frequently those solids collect are not adequately transferred so once the liquid has passed the solids dry in place, which then further retards the next solids to pass through the line and before you know it, you have a clogged line.

The solution was to reduce the diameter of the water closet fixture arm from 4" to 3". That reduction in line diameter effectively raised the level of the liquid enough to convey the solids effectively.

Now we see all forms of power flush, vaccuum and a number of other so called improvements in the fixtures all promising to eliminate the problems of clogged lines, but that is nonesense. Those improvements do improve how the solids are conveyed up and over the trapway in the fixture, but once the discharge enters the house DWV (Drain, Waste & Vent) system it is faced with the same problem as before.

When retrofitting older homes, the correct solution is to remove the 4" fixture arm and replace it with a 3" fixture arm.

Thank you lazypup for the helpful information. We've been hemming and hawing about our old toilet for over a year. The reality is that it doesn't flush solids all that well. But it never overflows or clogs, which is a plus.

Our home is a 1920s home. The toilet probably isn't original, but it's got to be at least 50-60 years old. I don't know that much about the stack, other than what I see in the basement, which is PVC. Does that mean the whole stack/plumbing is that way? We have a two story home, and the sole bathroom is on the 2nd floor.

I guess my concern about replacing the toilet is that I don't want it to be even worse. It's a nice, old toilet that works (well mostly). So I'm hesitant to replace it with a lower flow. But I know guests get pretty embarrassed when it doesn't all go down. I've been trying to diagnose the problem. Any ideas why solid waste doesn't go down? I read somewhere it could be build up in the holes in the rim. I've tried to clean them, and it helped somewhat.

Anyway, I hope more experts weigh in about toilets in older homes.