Slow Draining Gray Water Tank

[Beatcop49]

I have a White Hawk 23MBH, less than 2 months old. As instructed by the dealer, I close off black water tank, and keep open gray water tank. I wait until black water tank is 2/3rds full, then close off the gray water tank to fill it up. I then dump the black, rinse it, and flush out the sewer pipe with gray water....all as instructed by the dealer.

Today, I did just that again. My gray wasn't full, so I ran water in the galley sink to fill it. In just a few seconds, it was showing full...and I know, that it couldn't be...there wasn't enough water ran to fill it.

I dumped the black tank and rinsed it as I always do...no issues. When I went to open the gray tank valve, there was no immediate rush of water as it usually is....it ran very slow. It was as if the vent was blocked. I could hear gurgling in the tank as air tried to replace the water as it ran out.

I refilled the gray tank 2 more times, to the point that no more water would drain. The last time, it did drain better. I checked the vent on top of the TT, but it's capped and hard to tell if it is blocked...I really don't think it is though...nothing around me that can block it.

I'm also very careful about what goes into the tank...basically nothing except dish water and bath water.

Any ideas?

[mcfarmall]

I read the first paragraph several times but I still cant figure out what you mean. So does the gray tank dump into the black tank and then out to the sewer? My TT has a single 3" sewer outlet. There is a slide gate valve right at each tank. The sewage (black) tank line is 3" diameter from the gate valve to the discharge and the 2" diameter gray water drain joins the 3" at a "wye" fitting just upstream of the outlet.

From your description it sounds like the gray tank discharges into the black tank and then the combined water exits through a single main drain. I've never seen one plumbed in that way.

Most folks on here camp with the gate valves closed until their tanks are full or nearly full. They will open the gate valve on the black tank first, dump it empty, close the gate valve then open the gate valve on the gray tank to dump which also 'flushes' the hose with gray water. I have seen some TT's that have a separate sewer hose hookup for each tank instead of being plumbed to a common point. Usually this is on much bigger TT's than mine.

My buddy has a TT that has a black tank for the toilet only, a gray tank for the bathroom sink and shower, and a second gray tank just for the kitchen sink.

I dump a measured amount of water in the gray tank before you hit the road, say 10 or 15 gallons, let is slosh around in there on the way home then dump it when you arrive at your destination.

Seeing that your trailer is only 2 months old, I'd bet a dime that you have a plastic slug in the bottom of the gray tank that fell in there when the neanderthals at the factory hole-sawed the top of the tank for the sink inlet line. The slug found it's way to the discharge and acts like a dam with a 1/4" hole in it.

[norty1]

Sounds like some construction debris. Can you run a fish tape up in the outside drain with the valve open and dislodge it?
BTW stand clear when you do it.

[Beatcop49]

Originally Posted by mcfarmall

I read the first paragraph several times but I still cant figure out what you mean. So does the gray tank dump into the black tank and then out to the sewer? My TT has a single 3" sewer outlet. There is a slide gate valve right at each tank. The sewage (black) tank line is 3" diameter from the gate valve to the discharge and the 2" diameter gray water drain joins the 3" at a "wye" fitting just upstream of the outlet.

From your description it sounds like the gray tank discharges into the black tank and then the combined water exits through a single main drain. I've never seen one plumbed in that way.

Most folks on here camp with the gate valves closed until their tanks are full or nearly full. They will open the gate valve on the black tank first, dump it empty, close the gate valve then open the gate valve on the gray tank to dump which also 'flushes' the hose with gray water. I have seen some TT's that have a separate sewer hose hookup for each tank instead of being plumbed to a common point. Usually this is on much bigger TT's than mine.

My buddy has a TT that has a black tank for the toilet only, a gray tank for the bathroom sink and shower, and a second gray tank just for the kitchen sink.

I dump a measured amount of water in the gray tank before you hit the road, say 10 or 15 gallons, let is slosh around in there on the way home then dump it when you arrive at your destination.

Seeing that your trailer is only 2 months old, I'd bet a dime that you have a plastic slug in the bottom of the gray tank that fell in there when the neanderthals at the factory hole-sawed the top of the tank for the sink inlet line. The slug found it's way to the discharge and acts like a dam with a 1/4" hole in it.

I didn't think the description was that bad...close off black till nearly full. Close off gray till it is full. Dump and rinse black. Dump gray to clean sewer pipe.

Setup is same as yours....I've never heard of a gray tank that dumps into a black tank.

[norty1]

I have a external twist on bal terra valve that I uses to back fill the black tank from the grey.
Drain and flush the black, then close the twist on valve and open the grey, let it equalize( back flow into grey tank. ). Then close grey valve and open the twist on valve.
This may dislodge the obstruction.

[Beatcop49]

Originally Posted by norty1

I have a external twist on bal terra valve that I uses to back fill the black tank from the grey.
Drain and flush the black, then close the twist on valve and open the grey, let it equalize( back flow into grey tank. ). Then close grey valve and open the twist on valve.
This may dislodge the obstruction.

Thanks. May look at that. I'm not sure its an obstruction in the outlet though...its almost as if the vent is blocked. It may be...

[Salsa03]

Even if the vent was blocked, it would still drain... slowly and with some suction...but it woudl drain over time. If possible, try driving around with the gray tank valve open... it could disloge what ever is holding up water inside!

[Jmooney]

We are also careful about food debris from the kitchen sink that can build up at the point where the drain pipe meets the holding tank.

I occasionally put some of the black tank chems in the grey tanks as well to help break down debris and keep Oder down.

[Salsa03]

Originally Posted by Jmooney

I occasionally put some of the black tank chems in the grey tanks as well to help break down debris and keep Oder down.

Yes, I always put some of the stuff in the grey tank...better be safe


And yes, avoid flushing food debris and fats down the drain!

[mcfarmall]

Originally Posted by Beatcop49

I have a White Hawk 23MBH, less than 2 months old. As instructed by the dealer, I close off black water tank, and keep open gray water tank.

Originally Posted by Beatcop49

I didn't think the description was that bad...close off black till nearly full. Close off gray till it is full. Dump and rinse black. Dump gray to clean sewer pipe.

Setup is same as yours....I've never heard of a gray tank that dumps into a black tank.

Your original post stated "keep open gray water tank" That's why I read it several times and couldn't figure out what you were trying to say. Your reply in the second quote says something different, "Close off gray till its is full." I often get tripped up on small details.

[troutslayer]

Originally Posted by norty1

Sounds like some construction debris. Can you run a fish tape up in the outside drain with the valve open and dislodge it?
BTW stand clear when you do it.

That is what happened to ours. I use a Sewer Solution so there is a clear plastic fitting that allows me to see what is coming out of the drain (very entertaining ). Anyway, when our RV was new there was a piece of construction debris that blocked the hose to the Sewer Solution that I had to clear out before it would drain completely. Maybe a trip back to the dealer would be best since the unit is so new.

[Rolff]

slightly off topic. I always pour in eco-smart grey water treatment to help break down the waste and control smell.
Another trick I learned was to pour a bag of ice into the empty blackwater tank thru the toilet before we go anywhere. The motion while driving scours the bottom of the tank then when we arrive I add the treatment chemical and there is already water in it to dilute it.

[mcfarmall]

Originally Posted by Rolff

slightly off topic. I always pour in eco-smart grey water treatment to help break down the waste and control smell.
Another trick I learned was to pour a bag of ice into the empty blackwater tank thru the toilet before we go anywhere. The motion while driving scours the bottom of the tank then when we arrive I add the treatment chemical and there is already water in it to dilute it.

They say that the ice also scrubs any poo residue off the tank sensors...another added bonus.