Finished the sewer connection today and set the toilet. It seems like most people are going with composting toilets in tiny houses, but I’ve never been a big fan of indoor composting toilets. We had outside composting toilets on my off grid farm and it was a great setup, but here in the city I’d rather connect to sewer for a variety of reasons.
Fortunately Portland provides a legal route for tiny houses to connect to city sewer via a temporary RV drain plumbed to the sewer. What you do between your tiny house and the drain isn’t specified so we just followed standard plumbing practices.
First I pulled a tight string from the bottom of the tiny house drain outlet to the bottom of the RV connection and then measured the height from that point down to the ground every 4 feet.
Next we used a 3 1/2”hole saw and a drill press to cut support blocks for the pipe out of scrap 2x6s. The pipe is protected with pipe tape and fastened down to the blocks with plumbing tape as you would with any ABS installation. Connections between pipes are made with Fernco flexible connections so the whole system can be easily disassembled when the house needs to be moved and the pieces reused. For good measure we put a clean out at both ends of the 30’ above ground section. This might not be required but it certainly makes finding and dealing with problems easier if they occur.
Finally we covered the pipe with mulch so it’s out of the sun. We barely have 5/16” inch per foot slope on our pipe so fingers crossed for good drainage!
I remain a big fan of my Milwaukee torpedo level, it has a channel on one side which sits neatly over the pipe and useful markings for drain slope.
A quick tip for setting toilets: Toilet bolts have oblong heads that need to be oriented correctly in the channels of the toilet flange to hold it down securely. The problem is once you place the toilet there’s no way to see how these are oriented so what I do is mark the orientation of the head on the top of the bolt so I can be sure that it hasn’t spun sideways in the tightening process.
-Brian
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