What to do w/gray water on full hookup

[dwilli1]

Hi All. My first "full hookup" campsite and I'm wondering what to do w/ the gray water tank. I'm hooked up and was running gray water w/ the gate valve open to go directly into the septic but thought I should close it a couple days before we leave to have something to flush the hose from dumping the black water. What does anybody do here? I know to leave the black tank closed until we're ready to dump....should I just use the "flush" valve to help clean out the hose? or should I use some gray water to do that? Help is appreciated. Thanks!

[KyDan]

I always leave the gray water for last in order to flush the hose. There will be others chime in I'm sure.
This subject comes up a lot!
Happy Camping!

[cboss]

Originally Posted by dwilli1

I should close it a couple days before we leave to have something to flush the hose from dumping the black water.

Exactly. And let the black tank fill up a little also, it helps to break down the sludge. Always dump the black first, rinse out with the gray.

[eye95]

We keep both valves closed. If the gray tank fills, we partially empty it. We want as much gray water as possible to flush the sewer hose after emptying the black. We haven’t completely filled the black yet, so there hasn’t been a need yet to even partially dump it before the end of a trip.

On another forum, my wife read a post from a person who reported a sewer smell in his RV. He thought this shouldn’t happen because he left his gray valve open. Several people alerted him that this could actually contribute to the sewer smell if (for some reason) one of his traps was not blocking sewer gas.

My advice: Keep you valves shut. Dump only at the end of your trip or if a tank becomes full. If you either of your tanks becomes full, only partially dump it.

[BriaBeck]

We just treat a FHU site as a regular site with a dump station... we really don't do anything differently, except take a little longer showers and rinse the dishes a little better. We keep all the valves closed, and if a tank gets full, we just drain it.

[Jim34RL]

All I use are full hook-up sites. Depending on the length of stay I will leave one or both gray water tanks open till the day before we leave. I will than close them for cleaning out the sewer lines the day we leave. I also put a p-trap (drop the sewer hose down into a p-trap style from the sewer support) in the sewer hose to prevent orders from traveling back into the camper.

I have a clear Flush-King attached to the sewer pipe from the trailer which I use to clean out the sewer pipe and hose after dumping. You would be amazed at all of the gunk that is still in the sewer line from the trailer even after dumping the gray water tanks.

[smither]

I agree with eye95 and BriaBeck.

[dahagen]

I spend 6 months at a full hook up site in Arizona in winter. I leave black closed and grey open. I close grey the day before I dump the black, then use the grey water to clean out the hose. Then close black and leave grey open again. Make sure you use a good grease cutting dishwashing soap like Dawn in the grey water tank.

[sfsgm]

Originally Posted by eye95

We keep both valves closed. If the gray tank fills, we partially empty it. We want as much gray water as possible to flush the sewer hose after emptying the black. We haven’t completely filled the black yet, so there hasn’t been a need yet to even partially dump it before the end of a trip.

On another forum, my wife read a post from a person who reported a sewer smell in his RV. He thought this shouldn’t happen because he left his gray valve open. Several people alerted him that this could actually contribute to the sewer smell if (for some reason) one of his traps was not blocking sewer gas.

My advice: Keep you valves shut. Dump only at the end of your trip or if a tank becomes full. If you either of your tanks becomes full, only partially dump it.

And don't have the overhead fan in the bathroom on when you flush the toilet.

[bikendan]

Originally Posted by smither

I agree with eye95 and BriaBeck.

Ditto!

[Ourpod]

I remember a sleepless night before our first trip that had to dump the tanks. Good questions! We leave the hose connected to the gray tank, but keep the valve closed. If we take too many showers, we can then dump the dank to make some more room and take more showers! Keep the valve closed to avoid sewer smell from the park's system. Always flush the black tank first before leaving, then wash the hose with the gray water. We dump a bucket of soapy water in the toilet/black tank after dumping to help wash it out while we drive.

[eye95]

Originally Posted by sfsgm

And don't have the overhead fan in the bathroom on when you flush the toilet.

A lesson I learned by reading and not by doing. The least painful (or odiferous) way to learn.

[U.S.ArmyVeteran]

Originally Posted by smither

I agree with eye95 and BriaBeck.

2X...........absolutely!

[NXR]

If there is an issue with sewer flies at that location you will regret leaving the gray valve open. We had them at work once. Not good.

If you leave the gray open all the time you can have a build-up of food particles in the tank because there's no "whoosh" to float them away.

One thing I do is occasionally when driving between full hook-up sites is to pour part of a bottle of Dawn dishwashing soap directly into the rear bath sink. I put the drain plug in and fill the sink. Then I pull the drain plug and it whooshes the Dawn into the gray tank with minimum sudsing in the sink.

I leave about a third or half in the gray tank and the sloshing created while driving between sites washes the inside of the tank. Then when I arrive I dump the gray tank. Sometimes a lot of "stuff" comes out, even when the last dump seemed to be all clear water.

HTH,

Ray

[Witch Doctor]

I have learned to keep my tank valves closed even with full hook ups , you don’t want what ever is in the CG tank coming back into your RV. If you need to dump just dump. But leave all the tank closed.

[Larry-NC]

Originally Posted by eye95

We keep both valves closed. If the gray tank fills, we partially empty it. We want as much gray water as possible to flush the sewer hose after emptying the black. We haven’t completely filled the black yet, so there hasn’t been a need yet to even partially dump it before the end of a trip.

On another forum, my wife read a post from a person who reported a sewer smell in his RV. He thought this shouldn’t happen because he left his gray valve open. Several people alerted him that this could actually contribute to the sewer smell if (for some reason) one of his traps was not blocking sewer gas.

My advice: Keep you valves shut. Dump only at the end of your trip or if a tank becomes full. If you either of your tanks becomes full, only partially dump it.

In the wrong wind condition, with a sewer hookup and open gray valve, the wind can blow sewage odor back up the hose and out the vent stack on the roof. That odor could be drawn in by a vent fan blowing in, could drift in, or could even make it unpleasant to sit outside the RV. I can't think of a good reason to leave the gray valve open continually.

[n1acguy]

So far, I haven't left a pressure hose connected, and only fill the fresh water. When it needs to be refilled, I dump the black and then the gray in the usual way, and refill the fresh tank.
If we use the shower, I would probably connect a pressure hose and connect the sewer drain to the shower tank, leaving the shower tank valve open while in use, but only because I have a separate tank for the shower.
All of the places we've stayed at so far have had shower facilities that were a lot nicer and more convenient than the shower in the RV, so we haven't even used the shower yet, other than to confirm that it doesn't leak.
One of the reasons I do it this way is that the holding tanks will never overflow, and we don't have to be concerned about any plumbing leaks when we're gone for the day.

[Bhrava]

On my last trailer I let the grey fill since I was able to back flush the black with it, worked great too. This new trailer has two grey tanks, but the black tank is downstream and inline with the grey, so back flushing doesn't work. I still leave it closed and just dump as needed. When doing the black tank, I wait for it to flush clean then dump the grey tanks. I could do the p trap method for the sewer hose and leave the shower/bath grey valve open since I had to dump it twice on our 3 day stay, too many people liked the shower too much. I admit, I did too.

what is interesting, my panel has 2 black tank checks, I have no idea where the "second" tank is, nor what it's purpose is.

[eye95]

Originally Posted by Larry-NC

In the wrong wind condition, with a sewer hookup and open gray valve, the wind can blow sewage odor back up the hose and out the vent stack on the roof. That odor could be drawn in by a vent fan blowing in, could drift in, or could even make it unpleasant to sit outside the RV. I can't think of a good reason to leave the gray valve open continually.

I hadn’t considered sewer gas going out the vent stack.

That could cause the neighbors to have issues.

Yeah. Keep the stink sealed off.

[bubbles]

Originally Posted by Larry-NC

In the wrong wind condition, with a sewer hookup and open gray valve, the wind can blow sewage odor back up the hose and out the vent stack on the roof.

If there's wind blowing up the hose into the tank then the sewer connection is not done properly. The hookup is supposed to be a sealed connection.

Originally Posted by eye95

I hadn’t considered sewer gas going out the vent stack.
That could cause the neighbors to have issues.

The black tank continuously expels gas out a vent stack.