Micro Minnie Black Tank Flush Pressurizes With Water Pump

[Scoggins]

Winnebago Micro Minnie 1808FBS.

The hose that connects to the back of my sewage holding tank started to leak. I noticed that it only leaks when I pressurize the system with the water pump in the trailer. So there is fresh water from my water tanks leaking out of the hose when I pressurize the system. It seems weird to me that this line should be pressurized as I understood that this is a line to run fresh water through the holding tank. Am I correct or am I missing something? Thanks

 

[Morich]

We're missing the details to talk really close about the problem. Which RV is going to change the answers in many cases. But some generaal infomay be a start. Those are really terrible labels for me if I did not know what lines and valves an Rv normallay has.
The one that is marked woul see to be a connection to add pressure water to flush the solid waste tank and I would assume oterh to be for flushing the grey water tank, but that is not one I have seen before as I don't think of needing to flush a tank which shouold only hold soapy water at worst!
But that brings the question of what trailer this might be. Looking at the stabilizer jacks, I might guess it is a trailer?
But in either case, whether trailer or motorhome, the two holding tanks for waste should never get pressure as they should certainly have venting going up and out the roof! Much like a house, it would be dangerous to let sewer gas build up in the tanks!
Some kind of confusion seems to be involved as it is not possible to add water into a tank if there is no way for air to move out!

 

[Scoggins]

We're missing the details to talk really close about the problem. Which RV is going to change the answers in many cases. But some generaal infomay be a start. Those are really terrible labels for me if I did not know what lines and valves an Rv normallay has.
The one that is marked woul see to be a connection to add pressure water to flush the solid waste tank and I would assume oterh to be for flushing the grey water tank, but that is not one I have seen before as I don't think of needing to flush a tank which shouold only hold soapy water at worst!
But that brings the question of what trailer this might be. Looking at the stabilizer jacks, I might guess it is a trailer?
But in either case, whether trailer or motorhome, the two holding tanks for waste should never get pressure as they should certainly have venting going up and out the roof! Much like a house, it would be dangerous to let sewer gas build up in the tanks!
Some kind of confusion seems to be involved as it is not possible to add water into a tank if there is no way for air to move out!

I have updated the trailer description in the post.

The holding tanks are empty.

I believe the water coming out of the hose is fresh water from the fresh water tank. This suggests that fresh water is being forced out of that hose but stopped by a one way valve. This also means that when I connect an external water supply to try to swill the tank out that water is not able to enter the system due to back pressure. I usually get soaked when I try to dump the holding tanks.

If the valve I highlighted is not for swilling out the tank, then what is it for? I looked at the owners manual, it’s useless.

 

[Morich]

Okay, better idea of what is going on but also more confused as it should not happen!
But I am also very confused about the labels as they do not seem correct as you are reading them and I do see that they seem to mislead! !
They do seem very strange on several points as they seem so wrong!
This is the way I would expect them to work.

I think of drains on the waste and grey water tanks to be the big sewer hose size and coming out below the tanks using one single outlet where you connect the flexible hose to the place we drain. There should be a valve to let you first open the black tank to drain the solids and close that valve. Then there should be a second valve to open and drain the grey water through the same connectin to the dump site. Done in this way, it let us "clean/flush" any remaining solids out of the flex pipe before we store it in the RV! A bit cleaner than hauling the flex around with solid waste in it? Also the grey water tank opening has to be very near the bottom of the tank to fully drain, so a drain out the side doesn't seem correct!
Then there is the note at top right that says we only connect potable water here! This is because we use this port to fill the fresh water tank where we store the water we drink and cook with it! Good clean water only into the tank we drink from with NO connection to the waste tanks!
Then when we want to use a different hose at a drain point to flush, we have a note at top left saying to make sure the drain is open before we turn the water on to flush the tank. They give us a different hose at dump stations to avoid any chance of connecting anything we drink to anything we use for waste! If we fail to follow that yellow sign and put water pressure on the waste tank without first opening the drain, we might force waste up and into our face! That is not going to be a lot of waste if the vent is working to let the pressure go up and out but they simply do not want the chance of air and spray from the waste tank coming inside!
Never connecting any water we drink or eat with waste, is the basic main point!
So I think these labels should say there are two valves underneath, one to drain the black waste, another to drain the grey and they both have valves to let the waste go out the same main flex hose we connect to the sewer when draining. Main point on these is that it drains down using a common hose for ease of dumping both. One flex hose for two uses but only when we are dumping or flushing to finish! I read the warning at left for that connection for flushing the black tank!
The connection and label at right is for when we want to fill the fresh water tank, there is likely a vavle at the wet bay to send water to the tank or let us use the water inside by setting the valve to send it to faucets!
I'm not certain about there being a valve but I am guessing there is one to direct the water to the tank or for direct use from the hose.
But for the question of water forced out here when using the pump? There should normally be a check valve to keep water from the fresh water holding tank from going backward through the pump. Also there is usually a check valve built into the back side of this port to keep water from being forced out and down the RV side!
Note that the place where we connect the dringing water hose has a flap with stopper to keep things like bugs from going into that pipe where they might live in our drinking water? Good to keep that covered!
I think the bad label placement may be confusing you but if water tends to come out this hose connection when using pump, the check valve here may need a look.
Another small note to warn about high pressure if getting near mountains, etc. where pressure can be extreme?

See if that fits what you find and wish you luck on the new adventures!!
Hope it helps and solves some problems.
I am certain that MOST Americans do value our Canadian neighbors.

 

[Wmlunt-WO]

The connection on the right is the black tank flush.
The label on the right is for the 2 handles below, pull black to open the black tank drain, then run water into the black tank port previously mentioned, turn off black flush. Open grey tank handle and drain that tank.
Close all and cap before leaving.
The port on the left is the fresh water hookup, for use when hooked to full hook up site for fresh water into the trailer.
The fresh water tank fill is on the other side by the door to fill your fresh tank, and small 1/4 turn petcock for draining the fresh water tank.
Likely missing or someone pulled out the check valve on the fresh water utility hook up, portion the left, trying to fill the fresh tank, which doesn’t fill from there.
Bill

 

[Scoggins]

The connection on the right is the black tank flush.
The label on the right is for the 2 handles below, pull black to open the black tank drain, then run water into the black tank port previously mentioned, turn off black flush. Open grey tank handle and drain that tank.
Close all and cap before leaving.
The port on the left is the fresh water hookup, for use when hooked to full hook up site for fresh water into the trailer.
The fresh water tank fill is on the other side by the door to fill your fresh tank, and small 1/4 turn petcock for draining the fresh water tank.
Likely missing or someone pulled out the check valve on the fresh water utility hook up, portion the left, trying to fill the fresh tank, which doesn’t fill from there.
Bill

Thanks Bill. The connection on the right (the black tank flush) is the valve that is currently pressurized when I activate the water pump. I’m going to talk to the dealer next week. The left side port makes sense. The labels make no sense to me given that the labels for the satellite hookup to the left are below the ports.

 

[Scoggins]

Okay, better idea of what is going on but also more confused as it should not happen!
But I am also very confused about the labels as they do not seem correct as you are reading them and I do see that they seem to mislead! !
They do seem very strange on several points as they seem so wrong!
This is the way I would expect them to work.
View attachment 2503771
I think of drains on the waste and grey water tanks to be the big sewer hose size and coming out below the tanks using one single outlet where you connect the flexible hose to the place we drain. There should be a valve to let you first open the black tank to drain the solids and close that valve. Then there should be a second valve to open and drain the grey water through the same connectin to the dump site. Done in this way, it let us "clean/flush" any remaining solids out of the flex pipe before we store it in the RV! A bit cleaner than hauling the flex around with solid waste in it? Also the grey water tank opening has to be very near the bottom of the tank to fully drain, so a drain out the side doesn't seem correct!
Then there is the note at top right that says we only connect potable water here! This is because we use this port to fill the fresh water tank where we store the water we drink and cook with it! Good clean water only into the tank we drink from with NO connection to the waste tanks!
Then when we want to use a different hose at a drain point to flush, we have a note at top left saying to make sure the drain is open before we turn the water on to flush the tank. They give us a different hose at dump stations to avoid any chance of connecting anything we drink to anything we use for waste! If we fail to follow that yellow sign and put water pressure on the waste tank without first opening the drain, we might force waste up and into our face! That is not going to be a lot of waste if the vent is working to let the pressure go up and out but they simply do not want the chance of air and spray from the waste tank coming inside!
Never connecting any water we drink or eat with waste, is the basic main point!
So I think these labels should say there are two valves underneath, one to drain the black waste, another to drain the grey and they both have valves to let the waste go out the same main flex hose we connect to the sewer when draining. Main point on these is that it drains down using a common hose for ease of dumping both. One flex hose for two uses but only when we are dumping or flushing to finish! I read the warning at left for that connection for flushing the black tank!
The connection and label at right is for when we want to fill the fresh water tank, there is likely a vavle at the wet bay to send water to the tank or let us use the water inside by setting the valve to send it to faucets!
I'm not certain about there being a valve but I am guessing there is one to direct the water to the tank or for direct use from the hose.
But for the question of water forced out here when using the pump? There should normally be a check valve to keep water from the fresh water holding tank from going backward through the pump. Also there is usually a check valve built into the back side of this port to keep water from being forced out and down the RV side!
Note that the place where we connect the dringing water hose has a flap with stopper to keep things like bugs from going into that pipe where they might live in our drinking water? Good to keep that covered!
I think the bad label placement may be confusing you but if water tends to come out this hose connection when using pump, the check valve here may need a look.
Another small note to warn about high pressure if getting near mountains, etc. where pressure can be extreme?
View attachment 2503779
See if that fits what you find and wish you luck on the new adventures!!
Hope it helps and solves some problems.
I am certain that MOST Americans do value our Canadian neighbors.

Great, thanks. This helps although I agree that the labels are confusing especially given the labels for the satellite hookup to the right of these has a label directly below the port. Calling the dealer this week to determine what the different ports are given the state of the manual they provided. Cheers!

 

[Morich]

I think it will be the labels about draining the tank are to mean "look under here" and those will be two big handles to pull out , one for each tank to drain through the single pipe we see in the picture. There should be a point liely just back out fo sigth where grey and black join. Thing RV have two or three different ways to get water in for fresh water use. One is just a pipe/tube of some sort where we stick the hose, called gravity feed and thart only fills the tank. When we have that sort, there is usually a place to connect a hose and that provides for inside water when we don't want to use from the fresh water tank.
A bit easier is havign one hose connections where we put the pressure hose and have a valve someplace which we set to run water directly into the tank or set the other way, it should fill the fresh water tank! You may be able to spot that valve but the label is uncertain as they keep changing that part!
If the label is found and not clear on how to set it, there is way to find out. If we have the setting to fill the tank, it lets water run into the tank until it overflows and runs out underneath!
But if we have all the faucets, etc. inside turned off, we may hear the water run for a bit but stop pretty soon if we have it set to use inside as the water has not much space to fill and stop!
But it is often best to leave the pump turned off unless you are wanting to use that water. The idea is just being being a bit paranoid about trying to let the pump run when already has pressure from the outside source! Not a big deal to worry about, just I try not to make things work when not needed! One problem with getting in the habit of leaving the pump ion is that we may be out of the RV at some point and left the pump on. Us worry types think of coming back to water flooding the RV if something leaks!
Maybe I read about too many big failures here on the forum??

 

[Wmlunt-WO]

Thanks Bill. The connection on the right (the black tank flush) is the valve that is currently pressurized when I activate the water pump. I’m going to talk to the dealer next week. The left side port makes sense. The labels make no sense to me given that the labels for the satellite hookup to the left are below the ports.

There really is no other place to label the drain handles so they had to put them there. Mine has both handles labeled.
I don’t believe there is any valve to switch when filling fresh tank, that is an RV thing, I believe the MM have 2 fills, one for fresh fill on passenger side, and one for utility on the driver’s side.

Perplexed why water exits the black tank flush when pump is on. Does it also pressurize when the water is hooked up to the fhu Utility connection?
Maybe look at the check valve (air admittance valve) line. Could be someone hooked this up incorrectly and connected it to something in the fresh water feed lines to sink or shower?
It is usually located behind the wall where the black tank flush port is located, should be up high on that wall. Likely in a cabinet where you have to crawl up and look inside.
Does your black tank flush work? Do you hear the spray arm spinning when you use the flush port (with empty tank)?
I can see the left port in your picture pressuring as that is connected to the fresh tank, and if the valve for the winter antifreeze is connected wrong it could possibly pressurize the fresh tank???

 

[Morich]

I think it is down to confusion on what each connectioon does and not really prssure buiolding in the tanks. One reason for my thought on this is that each tank hasventing! We can add water to a tank if there is not an alternate route for the air inside to get out!
So that would mean we can't build pressure in a tank unless the air vent that goes out the roof is so totally stopped that water pressure can't blow it out!
The air admitance valve only acts to let the water go down the drain without sucking the water out of the trap.

 

[Old Navy]

The inlet circled in red is your city water hookup. The inlet on the left is your black water tank flush inlet. The labels for sewage and waste holding tanks are above the dump handles.

 

[That camper guy]

Winnebago Micro Minnie 1808FBS.

The hose that connects to the back of my sewage holding tank started to leak. I noticed that it only leaks when I pressurize the system with the water pump in the trailer. So there is fresh water from my water tanks leaking out of the hose when I pressurize the system. It seems weird to me that this line should be pressurized as I understood that this is a line to run fresh water through the holding tank. Am I correct or am I missing something? ThanksView attachment 2503614

I"ll demistify this whole thing for you. 1. WASTE WATER HOLDING TANK. this is the "label" for the drain valve "handle" of the Grey Water Tank. You'll find the handle directly below this label, under the trailer. 2. SEWAGE HOLDING TANK. Same situation. Look below this label and you'll find the T handle for the black water (sewage) tank. The hose connection on the left is for helping to wash or flush out the Black water tank when you're draining the tank. The hose connection on the right is to hook up to "city" water. Always use a pressure regulator heere. They run about $25-35.

 

[Wmlunt-WO]

So much misinformation here… the descriptions of the ports and handles as described by trailer owners are correct.
OP, please advise when you figure this out…
I think you will find the white hose connection is the one that you see as “pressurizing” likely from a missing check valve inside that inlet… when turning on the fresh water pump.