100' sewer drain

100 feet should not be a problem as others have said - that is if there is a decent slope.

Where we do our summer camping, my closest sewer hole is just over 30 feet so I use 2 x 20 feet of good slinky, not the failure prone low end blue. I also have to pass the slinky under the 5er to boot. No problem. I also have a Valterra accessory valve on the outlet for better dumping control. I dump the black, then close the Valterra valve then open the bathroom gray tank valve. This water then back flushes the black tank. I then close that valve and the Valterra and open the usually very full galley gray tank dump valve. Again, another back flush of the black tank. By this time, most if not all of the solids are out of the tank and down the drain. I'll usually go through 2-3 cycles with the black tank flusher as well and probably 20 gallons of water each time. To end it after all the 'stuff' has gone down the line, I then close whatever valves are open, and remove the slinky. That slinky may still have some 'stuff' in it when I slide it back under the 5er so I install a Camco hose flusher (it has a shut off on it)under the camper. Once on the other side, that Camco flusher shut off valve is opened while holding the slinky at waist height and most of whatever is in the hose siphons out. Once that's gone, I'll attach the dedicated black tank clean out water hose (it's a different color, so I KNOW which one to use) and give the slinky a good several minute flush out. This has been working for me for several years.

I have a power macerator as well as the water pressure version. Both work kinda OK but the method above seems to be superior and to me is straight forward.

Irelands child wrote:
100 feet should not be a problem as others have said - that is if there is a decent slope.

Therein lies the rub ... OP says 100ft all flat (i.e. no slope). I wouldn't try it without some kind of pressure motivating the flow.

Njmurvin wrote:

Irelands child wrote:
100 feet should not be a problem as others have said - that is if there is a decent slope.

Therein lies the rub ... OP says 100ft all flat (i.e. no slope). I wouldn't try it without some kind of pressure motivating the flow.

I don't know what he has, but he said it was flat. He didn't say it was level. It might not be correct to assume he has no slope.

Flat and level are two different things.

Just a quick update. Just dumped tanks with 100' sewer hose and had no problem worked fine just had to pick up hose and walk it to end. Then rinsed with gray water the same way.