Grey water tanks...

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SeaGal

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May 30, 2021
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43
Location
east of the river, west of the woods
We always leave the gray water tank valve open while camping. A couple of days before I need to dump the black tank I shut the gray tank valve to let the gray tank fill. Then I use that water to flush out the hose after dumping black tank.
I would be very careful about overfilling that gray tank that indicates 2/3 full. If you overfill it, you could rupture the tank.
The only sure way to find out what’s going on here is to open up the belly.
At this point I think you're right about opening up the belly.
 

SeaGal

Active member
Joined
May 30, 2021
Posts
43
Location
east of the river, west of the woods
The diagram below is not mine but this is the set-up we have. The galley tank dump handle is where it should be. What's missing is one of the dump handles forward of the sewer output and it appears it is the one from the black water tank, the one on the right. I'm guessing that because there's evidence of repair to the belly covering in that area. However, at the sewer outlet there is what I call a gate valve...similar image below.
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So the problem then becomes the existing dump handle (on the left) doesn't seem to be working...it doesn't affect the black water flow and it's not emptying the forward grey tank.
 

Rene T

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Farmington NH
That valve you showed a picture of is called a spin on valve. You want to keep that valve there all the time. It serves as a backup valve in case one of your tank drain valves are leaking a little when closed.
Also once you figure out your black tank valve issue what I do after dumping the black tank, I shut that valve then I open the gray tank valves and gray water will flow into the black tank. Then shut the gray valves and now you can dump the black tank using transferred gray water. I can typically do this a couple of times.
 

SeaGal

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Joined
May 30, 2021
Posts
43
Location
east of the river, west of the woods
Thanks to all of you who responded with advice and experiences. Problem solved. First, the sensors are not correct. Secondly, the valve at the sewer line outlet is the black water valve, the only black water valve. The handle forward of the sewer line is for the front grey tank - the cable was loose and the tank was empty though it was reading 2/3 full. It took dropping the belly pan to determine that.

These units were built with two pull handles side by side forward of the sewer line, one for the grey (grey tank 1) and one for black water tank as the diagram in post #23 shows, with the galley tank (grey tank 2) pull handle just forward of the front wheel. Apparently the original owner had that system modified because the hole through the belly pan where the black tank pull rod would be has been repaired with a small black tarry type patch. A Cedar Creek service rep told me that that's what they use to patch the underbelly. So, now I guess we can shower...it's been days and days. lol

Thank you again. :)
 

Edd505

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Mar 22, 2021
Posts
137
Location
Elephant Butte, NM
Thanks to all of you who responded with advice and experiences. Problem solved. First, the sensors are not correct. Secondly, the valve at the sewer line outlet is the black water valve, the only black water valve. The handle forward of the sewer line is for the front grey tank - the cable was loose and the tank was empty though it was reading 2/3 full. It took dropping the belly pan to determine that.

These units were built with two pull handles side by side forward of the sewer line, one for the grey (grey tank 1) and one for black water tank as the diagram in post #23 shows, with the galley tank (grey tank 2) pull handle just forward of the front wheel. Apparently the original owner had that system modified because the hole through the belly pan where the black tank pull rod would be has been repaired with a small black tarry type patch. A Cedar Creek service rep told me that that's what they use to patch the underbelly. So, now I guess we can shower...it's been days and days. lol

Thank you again. :)
Thanks you diagram is exactly like my KZ tanks. I know you will find a cable operated gate valve, open to dump. Glad your fixed, we save a lot when we can share info and DIY.
 

Jack Ducan

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Joined
Jul 1, 2021
Posts
11
Location
united states
A dirty gray or black water tank sensor can produce a smelly problem that makes RV less enjoyable. So, the steps to clean RV holding tank sensors is: First, Drain your gray holding tank and close the tank’s valve. Then, fill your holding tank, add cleaning agent. Open the tank valve and drain the contents, use a pressure washer to spray a powerful water stream through kitchen sink or bathroom drain. Continue dumping holding tank’s content and refilling it with water by opening all RV faucets and showerheads. Ensure to close the valve every time you top up the tank and open the valve when draining.
 

Edd505

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Joined
Mar 22, 2021
Posts
137
Location
Elephant Butte, NM
A dirty gray or black water tank sensor can produce a smelly problem that makes RV less enjoyable. So, the steps to clean RV holding tank sensors is: First, Drain your gray holding tank and close the tank’s valve. Then, fill your holding tank, add cleaning agent. Open the tank valve and drain the contents, use a pressure washer to spray a powerful water stream through kitchen sink or bathroom drain. Continue dumping holding tank’s content and refilling it with water by opening all RV faucets and showerheads. Ensure to close the valve every time you top up the tank and open the valve when draining.
I can guaranty sensors do not cause any smell but that they are notoriously inaccurate. I bought a new 5W and within months the sensors quit being accurate. This was not my 1st RV so I dump & flush properly, black, kitchen gray, shower gray, flush black at least once, use a clear plastic fitting so you can see the water is clear flushing the black, done. Use a pressure washer, please post a video or pictures. Most tanks smells come from air admittance valves that malfunction.
CheckValave.jpg
 

Jack Ducan

Member
Joined
Jul 1, 2021
Posts
11
Location
united states
A dirty gray or black water tank sensor can produce a smelly problem that makes RV less enjoyable. So, the steps to clean RV holding tank sensors is: First, Drain your gray holding tank and close the tank’s valve. Then, fill your holding tank, add cleaning agent. Open the tank valve and drain the contents, use a pressure washer to spray a powerful water stream through kitchen sink or bathroom drain. Continue dumping holding tank’s content and refilling it with water by opening all RV faucets and showerheads. Ensure to close the valve every time you top up the tank and open the valve when draining.
 

Edd505

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Joined
Mar 22, 2021
Posts
137
Location
Elephant Butte, NM
From your link: Are you wondering whether your tank is already full of gunk or not? Learning how to clean RV holding tank sensors can save you the hassle of a smelly motorhome because of overflowing liquid and human wastes.
The sensor does not cause the smell. the tank that not empty does, the sensors a part in the system and parts do not cause smells. This is how to clean those sensors and hopefully to know the level of the tank contents. I believe most Rvers know the inaccuracies of in tank sensors, there any number of articles on it. There is a company that makes external sensors that claims to fix the issue. Your post would be like shoes cause foot odors, I stand by the original post.
 

steveblonde

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Jan 8, 2015
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3,781
Location
calgary alberta
We do and it works a treat, from the sewer end up, using a jetter hose. 🙂
Jack duncan said

. Open the tank valve and drain the contents, use a pressure washer to spray a powerful water stream through kitchen sink or bathroom drain.

What i meant was i would never do it this way i would THINK you would destroy the plumbing under the sink
 

jackiemac

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Feb 22, 2016
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6,097
Location
Scotland
Jack duncan said

. Open the tank valve and drain the contents, use a pressure washer to spray a powerful water stream through kitchen sink or bathroom drain.

What i meant was i would never do it this way i would THINK you would destroy the plumbing under the sink
Agree.
 

Rene T

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May 20, 2011
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Farmington NH
As soon soon as the pressure of the water gets to the outlet of the trap, there would not be any forceful pressure to accomplish anything.
 

Edd505

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Mar 22, 2021
Posts
137
Location
Elephant Butte, NM
Jack duncan said

. Open the tank valve and drain the contents, use a pressure washer to spray a powerful water stream through kitchen sink or bathroom drain.

What i meant was i would never do it this way i would THINK you would destroy the plumbing under the sink
explain how you get around the P trap? The metal/silver pipe goes the the sink drain. I hate to be argumentative but people come here for accurate information, I can see someone new reading your use a pressure wash making a real mess in their to them new RV.
 

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steveblonde

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calgary alberta
If it were me i would just use liquid plumber if its blocked. If its not blocked and your getting a smell i would empty the tank and close the valve. I would then pour about 1/2 of the tank capacity of fresh clean hot water down the drain with a couple cups of bleach. Then go for a drive the sloshing will help clean any particulate.
So do it before your next trip.
 
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