Easy Backflushing to Clear a Clogged Black Tank

[djgodden]

I occasionally experience a blockage of my black tank when draining. We use "normal" house toilet paper for a myriad of reasons. Yes, I know it's not recommended. But I found a quick and easy way to clear a blocked line. I use the gray water tank, it should be full or nearly so to accomplish this.

I purchased an accessory gate valve which connects to the plumbing drain line and then connect my dump pipe to that. This allows me shut off the dump flow while leaving the gray/black valves open. Don't panic yet, I'm not contaminating grey with black. If I see I've got a black blockage I close all valves, wait until the flow stops and then close the accessory valve. Then I open the grey water tank until the pipes are full, usually gurgling followed by silence. Then I open the black water valve. The pressure of the gray water is greater than the black and the gray water backflows into the black tank. I wait a about 30 seconds, then close the gray water valve and then open the accessory valve.

This works great for me, never failed to clear a black blockage in seconds.

[JC2]

In addition to obviously needing to use more water when using, I mounted one of the flush valves on the side of our black tack in years past when we have a 5th wheel. Use clear silicone sealant and "snug" the mounting screws. Do not over tighten!! Ours actually sprayed all over the inside of the tank and did a pretty good job. We used it about every 2-3rd time when dumping depending on how many other folks were waiting. I really don't see how the ones mounted on the clear discharge valves can get up inside the tank very well. Another possible option is a wand type device with an on/off valve that is attached to a water hose and then brought into the bathroom via through a bath window or through the front door and stuck down the toilet before turning on. Sounds kinda gross to me.
https://www.rvsupplyparts.com/catalog/rv-holding-tank-flush-kit/valterra-no-fuss-flush-holding-tank-...

[JC2]

2oldman wrote:
Perhaps you need to use more water when flushing.

Bingo. And once again, H2O to the rescue.:W

[Dutch_12078]

I agree with 2oldman, it sounds like a lack of water problem rather than the TP being used. We've used Charmin Ultra Soft for many years in multiple RV's with no problems. Pretty much any TP labeled "Septic tank safe" or similar should work fine with enough flush water. That said, we also have a third twist-on valve in place that we use to either back flush the black tank just for more thorough cleaning or to allow the tanks to equalize when we need additional capacity when no sewer hook up is available. It's usually the grey tank that needs the extra capacity, so the flow is normally from the grey to black in that situation. I don't have any concerns with the two tanks "cross contaminating" though, since it's all sewage that's going to end up in the same place.

[STBRetired]

Better yet, try one of these:

Tank Rinser

[2oldman]

Perhaps you need to use more water when flushing.