Home - Waste Dump

Lakejumper wrote:
Thank you everyone! Great feedback! We’re using the existing pipe diameter.

Good call and another "Happy Ending" on RV.NET :B

Thank you everyone! Great feedback! We’re using the existing pipe diameter.

pitch wrote:
Code will dictate the proper size.

OP is using an existing clean out under the house and will be extending it outside. If the clean out pipe size is 3" you sure don't want to increase it to 4" and if it's 4" you sure don't want to decrease it to 3".

So as I said before whatever size it is that is the size pipe that needs to be used.

So let's say the existing clean out is 3" and current code says 4". What do you suggest the OP does then???

OP, extend what is there and be happy!

Code will dictate the proper size.

Where I used to live, there was a 3 inch clean out and 3 inch terra cotta pipe. Clean out was under the trailer 4 feet from the trailer connection. I connected straight to it with some 3 inch adapters and it worked fine.

Our in town house has a clean out at the property line right into the city sewer. I don't know what size it is but my DP drain hose screws right in to it. Built that house 5-6 years ago and have used it ever since.

More important than the pipe size is the slope. To flat, it all will lay in pipe. Too steep, and the liquid will leave the solids to lay in pipe, dry out, and start clog.
And make sure the pipe is supported to hold the weight of a full pipe, so the slope does not change.
Same flow volume, same slope, the smaller pipe will have a deeper stream, less likely for floaters to bottom out. This gets to be important because most waste tanks drain out the side. The last few inches drains progressively slower.

3” is more than enough for a RV dump.

Bottom line pipe it the size of the clean out.

The sewer line from our cottage to the septic system is 4" PVC running right behind the RV pad. I had the contractor install a 4" sanitary 'T' and riser with a 4" cleanout cap where it's convenient to connect the stinky slinky when he installed the new system.

Dick_B wrote:
I'm thinking the plumber would decide that but I think ours is at least four inches; probably more like 6.

If you plan to use it both as a Sewer clean out and RV dump go with the size of the sewer line.