Gray Water Drainage Issue

[DanielHenry]

Near the end of my last trip my gray water sensor indicated that tank to be half full after being fully drained.  This was a first for me, but I figured it was like the black water tank with dirty sensors.  My plan was to first drain the gray water completely.  Then I refilled this tank while flushing down an enzyme packet into the kitchen sink. To fill this tank I turned on all the taps including the shower.  The sensors never showed more than half full, but I suddenly noticed that the shower pan had 5-inches of standing water.  The rig was on a slight slope toward the rear where this shower is located.  I thought that due to the slope that I had overfilled the tank and that caused water to collect in the shower pan at the lowest part of the rig.  My first thought was to drain some of the gray water until the shower pan emptied.  Unfortunately after draining all of the water from the gray water tank the same amount of water remained in the shower pan. I tried to use a plunger to free up any blockage, but this failed to help. I next bailed water from the shower pan and poured it into the adjacent bathroom sink.  After 2 buckets of water I saw the water backing up into the shower pan.

Any thoughts about the possible cause and how to fix this? Perhaps this is a blockage in the drain that connects to the sink and shower pan to the gray water drain.  I went underneath and looked for this drain line, but it isn't exposed as best I can see. Could this be a blocked vent or failed vacuum break?  Or, are vacuum breaks only used for black water tanks?  Where would this be located if there is one?

Any suggestions would be appreciated.

 

[Henry J Fate]

Try to get the rv level then see if things drain. If not, try again to locate the plumbing line to the shower drain. It is common to find slip couplings used and sometimes these type of couplings will move on the pipe from normal use or possibly from trying to unblock the drain line.

You can also try a good Wet/dry vacuum in the drain to pull out any standing water or slime that might be in there. It is also possible to use a water jet to spray into the drain line to clear it out.

It is possible you have a blocked vent from not being level or from a drain line that has moved.

Forget about the tank sensors for now.. Use your good judgement  to determine when the tank is getting full. Finding a place to physically look at or in the tank is always best. Tank sensors are rarely reliable and eventually you will be able to manage tank levels without sensors.

 

[Rene T]

How long have you owned this RV and what brand and model is it?
If you have another gray tank try emptying it and see what happens.

 

[Gary RV_Wizard]

There will be vacuum breakers (air-admittance valves) under each sink - it's a vertical pipe with a flapper valve on top. There will also be a tank vent up to the roof.

It sounds like you have a blockage in the waste line going to the tank, but being off-level can make the water drain in the wrong direction (away from the tank). There isn't a lot of pitch in RV drain lines.

Yes, gray tank sensors can get gummed up just like black tank sensors, but that's the least of your worries now.

 

[cavie]

Near the end of my last trip my gray water sensor indicated that tank to be half full after being fully drained.  This was a first for me, but I figured it was like the black water tank with dirty sensors.  My plan was to first drain the gray water completely.  Then I refilled this tank while flushing down an enzyme packet into the kitchen sink. To fill this tank I turned on all the taps including the shower.  The sensors never showed more than half full, but I suddenly noticed that the shower pan had 5-inches of standing water.  The rig was on a slight slope toward the rear where this shower is located.  I thought that due to the slope that I had overfilled the tank and that caused water to collect in the shower pan at the lowest part of the rig.  My first thought was to drain some of the gray water until the shower pan emptied.  Unfortunately after draining all of the water from the gray water tank the same amount of water remained in the shower pan. I tried to use a plunger to free up any blockage, but this failed to help. I next bailed water from the shower pan and poured it into the adjacent bathroom sink.  After 2 buckets of water I saw the water backing up into the shower pan.
Any thoughts about the possible cause and how to fix this? Perhaps this is a blockage in the drain that connects to the sink and shower pan to the gray water drain.  I went underneath and looked for this drain line, but it isn't exposed as best I can see. Could this be a blocked vent or failed vacuum break?  Or, are vacuum breaks only used for black water tanks?  Where would this be located if there is one?




Any suggestions would be appreciated.

Many RV's have 2 gray water tanks. Some RV's have a 2nd gray water valve on the curb side of the Rv. How old is your RV. Is it a motor home?

 

[skydivemark]

Near the end of my last trip my gray water sensor indicated that tank to be half full after being fully drained.  This was a first for me, but I figured it was like the black water tank with dirty sensors.  My plan was to first drain the gray water completely.  Then I refilled this tank while flushing down an enzyme packet into the kitchen sink. To fill this tank I turned on all the taps including the shower.  The sensors never showed more than half full, but I suddenly noticed that the shower pan had 5-inches of standing water.  The rig was on a slight slope toward the rear where this shower is located.  I thought that due to the slope that I had overfilled the tank and that caused water to collect in the shower pan at the lowest part of the rig.  My first thought was to drain some of the gray water until the shower pan emptied.  Unfortunately after draining all of the water from the gray water tank the same amount of water remained in the shower pan. I tried to use a plunger to free up any blockage, but this failed to help. I next bailed water from the shower pan and poured it into the adjacent bathroom sink.  After 2 buckets of water I saw the water backing up into the shower pan.

Any thoughts about the possible cause and how to fix this? Perhaps this is a blockage in the drain that connects to the sink and shower pan to the gray water drain.  I went underneath and looked for this drain line, but it isn't exposed as best I can see. Could this be a blocked vent or failed vacuum break?  Or, are vacuum breaks only used for black water tanks?  Where would this be located if there is one?

Any suggestions would be appreciated.

Not all bathroom sinks drain into the black tank. Our first rig, the bathroom sink drained into the gray tank, but our current rig it drains to the black tank so it's possible when you were bailing water it was going right back where it came from.

 

[cavie]

delete.