Draining Black Water Tank on 27RLSWE

[Jim-JoanR]

We are unable to completely drain the black water tank on our 2014 Cougar 27RLSWE. After draining and flushing the black water tank we still have 1 inch of water in the tank directly under the toilet. I have repeatedly filled the tank using the black water flush, dumping buckets of water into the toilet to fill the tank, and filling the tank using a hose through the toilet valve. In all cases, after I dump the tank there is still 1 inch of water in the tank directly under the toilet. Is this normal? Or unusual? If not normal, what could be the cause.

I could sure use some advice.

Thanks

[therink]

I have had my valve off of my black tank to repair it. I can say that on my tank, the outlet flange is not at the lowest part of the tank. The floor of the tank is maybe 1/2" lower than the bottom of the valve flange, therefore it never completely drains.
I am fairly sure most late model Keystones have the same style tanks.

[chuckster57]

It's not uncommon at all for the outlet to be at a slightly higher elevation than the center of the tank. There isn't enough material to mold the outlet and retain strength. As long as it's clear, clean water you'll be fine.

I doubt Keystone makes their own tanks as this is common in pretty much every holding tank I've seen.

[hankaye]

Jim-JoanR, Howdy;

Could be a lack of support under the tank, not enough
for it to fall out of the framework, but enough to allow
the tank to sag the length of the bottom allowing water
to accumulate ...

hankaye

[Ken / Claudia]

Check your manual about how to use the black tank flush or see the label near the inlet. Mine says to be sure drain valve is open when using. The salesman said same thing. I do not know if you can or will cause damage by using it to fill the tank. I have not used it with closed dump valve to see what happens. Regarding getting all water out of any tank, likely a little left in them and just put some rv anti freeze down toilet and each drain for winter storage. I been doing that for about 30 years and no holding tank freeze problems yet here in Oregon. I have had 2 other water freeze problems one at the toilet and a water line freeze crack once.

[chuckster57]

The sticker that says the valve must be open to use is there to cover Keystone from liability regarding use of the flusher.

If you hook up a hose to the flusher, close the drain valve and turn the hose on, your just going to fill the black tank. If you LEAVE IT ON, then it will completely fill the tank and start "backing up". It will do one of three things at this point.

1) continue to back up through the vent and then cause a poo volcano.

2) continue to back up and cause your toilet seal to let loose, flodding your trailer with yuck water.

3) put enough pressure on the tank to split it open and fill your underbelly with.... you guessed it.

I routinely hook up the flusher, turn the water on and close the valve. I set a timer for 4 minutes so I don't forget to open the valve.


When you winterized, there is no reason at all to put antifreeze in the waste tanks. They are like ice cube trays, the water may freeze but it has room to expand UP into the air space. The only danger is to the drain and valve. If there is enough water against the valve to fill the drain line, it can freeze causing issues. Some members leave the valves open with a bucket underneath to catch any moisture, my thoughts are if the LAST thing you do after storing and winterizing is pull the valves open and drain any liquid you can, you'll be okay to close them for the winter.

[Jim-JoanR]

Thanks everyone, for the advice and information.

Jim