Howzis theory?

[gdavis62]

Clipped from another site:

4 in. soil pipe offers a more efficient way to dispose of solid material, but the introduction of low-volume toilets and other water-conserving measures, significantly reduces the level (height) of water in the pipe, resulting in significant clogging within the soil pipe. In new construction, the 4-in. pipe is now too wide for long, horizontal runs (especially between the home's main vertical drain, or stack, and the street).


3-in. soil pipes raise the flow level in horizontal runs and, as a result, suffer fewer clogs.

[PLUMBER RICK]

agree, but you also have to keep in mind that other fixtures help to wash the line.

as i've mentioned in other post, powder rooms separated from the common main are an issue. keep toilets within 30' of the rest of the fixtures, such as laundry and showers. not required by code yet:confused:, but just real life experience with new and service work.

rick.

[gdavis62]

The reason I was wondering, is because the plumber we've hired changed all the 3" sewer lines under the slab from 3" to 4".

Special-order fittings were put on order, but the work won't happen for a week or so.

If you were me, would you discuss with him and go back to 3"?

I ordered that Code Check book and two others (Rex's and someone else's) and am planning to spend a few hours at the town hall examining the code books. I'm enjoying getting somewhat up to speed on this.

[Aaron91]

I've read it in several of my books. The main 'fact' behind this all is the older toilets as we all know used 3+ gallons a flush, which 'filled' the 4" pipe quite well. Now with toilets being limited to 1.6 gallons a flush theres a larger air pocket in the 4" lines. Which makes a 'drag' effect on the waste. I would not see the 3" pipe in the ground being a problem at all.

[Gene Bickford]

Reading this thread reminds me of a question I've had for a while.

One of the last projects I worked on was a sewer rebuild. Each service from the main to the property line was "up graded" from a 4" to 6" with min pitch, sometimes less. These services were for single and two family homes. I tried to argue the low flow theory with the inspector and the engineer but since they could make my job ten times harder I didn"t push the issue very hard.
Am I wrong in thinking this is going to cause a problems?
It's not just toilets that are low flow. It seems everything is "low flow" now adays. Dish washers, washing machines, shower heads etc..
Not much flow to wash out a 6" line.

[Aaron91]

A 6" sewer line for a single/dual family is ludacris. What size was the main sewer line you tied into then?

[Gene Bickford]

Yeah! That's what I'm thinking. The main is only 8", I just don't get it:confused: .
This is in an old neighborhood so it's not like they are anticipating some big condos or something in the future. But since I don't have smart people papers ( degree) I must not know what I'm talking about.
I guess I still could be wrong but I'm thinking NOT.

[Woussko]

Seems like maybe it's time for the ROYAL FLUSH before bed time if not several times per day. The ROYAL FLUSH is the rapid pouring of 8 gallons (2 almost full 5 gallon pails) or more of water into each toilet bowl. You start with the farthest one for your sewer line and work towards it and most likely end up with a basement toilet. Be sure to have someone watching for backups just in case one happens.

People can say what they like, but I really would love to have my old 5 gallon per flush vintage American Standard toilets back. They had to be replaced for various reasons. Even they won't last forever.:(

[Bogart]

Two toilets are the max on 3" pipe. Wet vents help. PVC pipe is so much smoother than cast iron that 3 or 4 inch won't really matter.

[ToUtahNow]

Two toilets are the max on 3" pipe.

You are correct for a 3" horizontal branch in Illinois but not in areas with the UPC three water closets are the max on a 3" line.