One thing that would help is to have no unions at all in the drain pipes. Give each drain a dedicated path to the sewer with as few bends as possible. And design the drain pipes so that they go straight down for a while before bending. Having a long, vertical tower will mean that any clog will happen lower in the pipe and the tower of backed up water between the clog and the drain port will exert force on the clog to push it out of the way.
Actually, that would make things terrible. If a drain line is sloped too much, the slower-moving solids tend to sink out of the faster-moving water, not too different from an unsloped line where everything just sits where it is. You need to either be at 1/4"/ft or vertical.
Also, a too-large pipe will accumulate crud faster than a properly-sized pipe due to diminished flow velocity, aka scour.
It doesn’t look like it, but there really is a huge amount of engineering that’s been sorted out in modern plumbing. Most of it was learned by “Goldilocks” trial and error over many years.
Participants in this thread should consider “The Deacon’s Masterpiece (or, The Wonderful One-Hoss Shay)” by Oliver Wendell Holmes, for a study on construction strategies meant to last.
Thank you, I’m glad someone brought this up. “Just make everything huge” isn’t always a solution, and can be counterproductive. Is PEX resistant to mineral buildup because it flexes and causes any precipitate to flush out, or have we just not used it long enough to see much of that yet?
What’s the deal with those waste grinders you use to pipe shit upwards before it exits? (These are commonly found in below-grade basement toilets, right?) Would those be useful in this mega plumbing scenario or are they just another failure point?
The plumbing code most likely would not allow it, neither the environmental impact, but yes it’s very possible.
You basically need a stream of water below your (elevated) house that all waste falls into, basically no pipes beyond ‘aim and drop’, no traps either. That would take care of the waste lines at least. Now the supply is going to be tricker as water freezes, but careful site selection may get you an artesian well or perhaps tap into a spring from a source uphill from you you can tap into under the frost line.
This is only true assuming a perfect installation. Most 1/4"/1’ drops have flat places in them because the plumber screwed up. I get to fix them on a regular basis. It’s also why waste can stop flowing when you get a partial clog it is easier to backup a slightly sloped line. On the other hand a 6" line can have pounds of waste clogging it and still maintain a normal flow path. If you look at a normal 4" main drain line in a home the 6" line will have a cross sectional area 2.25 times larger. The blockage will most likely be on the low side as you said due to solids settling out but waste can overrun those blockages and still maintain a nominal 1/4" drop rate. You would have to have a blockage bigger than 2" deep and 8’ long before you lost the normal flow path.
You’re right my system would have a lot more blockage than a traditional system but you wouldn’t know it was there for a very long time.
In this case though I think its the only way to make a maintenance free solution. At a certain point you could be dumping waste into a box and as long as it doesn’t fill up in a century you could meet the OPs criteria. but a 4mm gallon box below your house didn’t fell as fun to write about.
It’s an electric motor, a pump mechanism, and seals to keep the yuck away from the wiring. If you ignore it, it’ll last five to ten years. Some preventative maintenance can get it to last maybe twenty years. So yes, it’s a definite point of failure, and one you need to plan for.
One thing that may help avoid clogs would be to have the drain pipes expand gradually between the drain and the sewer. So rather than the pipes being a straight cylinder, have them be slightly conic in shape, like a reverse funnel. This way if a clog does try to form, the downstream of the pipe is always just a little bit bigger than the upstream and the clog should be able to slip forward.
Rather than build one plumbing system to last 100 years, just build 100 houses with decent plumbing and the minute there is a plumbing issue, move next door. Repeat for 100 years. Houses should be disposable, not permanent. Bezos can afford it.
I suspect that’s the real answer. Not necessarily aim to make the system maintenance and trouble-free, just reasonably trouble-free, and as easy maintenance as possible. That’s the sort of stuff that might make a system like that last a few hundred years.
IANAP but I feel it would be possible to design a system of high pressure water lines that are hooked up to the regular drain lines. And have a system of valves that seal off the lines at the drains in the various sinks, tubs, and toilets. That way you can blast out any obstructions in the lines on a regular basis before they have a chance to form blockages. You could automate the system so it flushes out the pipes a few times every day.
While that may prevent blockages, that sounds like the sort of thing that would require maintenance of equipment and has the potential to crack pipes and cause other damage.
Hey, it worked for Hercules.
But then it’s important to warn everyone “Don’t be holding your breath until you hear it hit bottom.”
(Based on a joke actually told to us by our Grade 3 teacher.)