Black Water and Gray Water Tank Tips

In our posts in the tips and tricks section we are creating,  we are going to post some of the items we were a little confused about and needed some help with.  If we needed some help and explaining on these items, we are sure others out there could use some advice to, and our first confusing situation came up with the black water and gray water tanks, their differences and how to hook up the drain pipes at a campground or dump station. So here’s what was explained to us and I hope it helps you!

Black Water Tank
The only water that gets stored into your black water tank is the water from your trailers toilet. The sinks, showers, and any other rinse down system where the water is caught does not go into this tank.
Gray Water Tank
This tank holds the water that goes down the drains in your kitchen sink, bathroom sink(s) and the shower drains. None of the water from the toilet gets stored in this tank at all.

OK so now we have differentiated between the two tanks and understand their purposes, that will help in understanding the draining procedure outlined later in the article. Inside the rv/trailer, you will have a control or switch panel, and on that panel will be a group of small push buttons and a series of small lights to act as a gauge. When you need to know and watch how much each tank is holding, all you do is push down the button that is labeled for the tank you desire to read and look at the indicator lights. Now one thing that comes to mind as this is being written, I have not learned yet thankfully what happens if the tanks get overfull, or is there some safety feature to stop the flow back into your trailer or RV. Maybe someone could comment on that situation, remember, we are always still learning.

Now its time to hook up and drain your tanks. Don’t worry it’s not all gross and nasty and disgusting, and if done right you will hardly even smell anything bad. I did say hardly, not you won’t. Now it’s time to get out your flexible hose sections, all the fittings and elbows, and lay them out on the ground by the campers tank drain port.  Also one additional item we purchased as a suggested buy from a fellow camper, was a short piece of clear plastic see thru drain pipe so you can watch the filth or cleanliness of the draining water, it helps. I like to put the clear piece up at the RV/trailer side where I can see it as opposed to the end at the drain hole in the ground, which may be 15-20 feet away and hard to watch.

So here’s the basic steps to hooking up properly and staying clean

trailer sewer valve

1 – Make sure both the gray water  and black water tank drain handles are pushed inward to the closed position before removing the cap.

rv sewer hoseclear sewer adapter

2 – Remove the cap from the drain port and install the clear plastic see-thru drain pipe extension if you have purchased as was suggested to us.  If you don’t have one, this is the time to install your first length of flexible pipe by lining up the round nubs on the port and the retaining tabs on the pipe. Now twist until you feel them bottom out and seat securely.  Check to see if you have enough hose length to reach to the sewer hole fitting at your site, if not its time to add-on another section of pipe, just line the nubs and retaining fingers up, and again twist real hard and tight until the nubs hit the end of the retainer slot.

sewer elbow

3 – Now remove the screw on plastic cap from the sewer drain fitting in the ground at the site.  At this point we will take the fitting with a 90 degree elbow and with all the different thread sizes on it, and gently screw it down into the ground pipe.  DO NOT over tighten this it is not necessary, just make it snug and either unscrew or tighten, which ever is easiest to get the elbow to point in the direction of the flexible hose.  Now as with the hose when attaching it to the trailer, line up the nubs of the elbowed fitting and the retainer fingers on the hose, and once again until you feel and see the nubs have seated all the way to the end of the retainer slots.

serer hose support packedsewer hose support extendedsewer support installed

4 – The final step is to install the pipe support apparatus that accordions out to match whatever length you need.  The higher end starts near the trailer and the lower end should be at the ground sewer pipe fitting.  Now gently lift the hose and slide the slanted supports under the hose to give it a downhill slope to allow all the water and material to flow away from the trailer and into the ground pipe fitting.

That’s it, you are now hooked up and ready to drain your tanks.  The first tank you will always want to drain is the black water tank.  This is done because there will be some substance to the material coming from that tank and running through the hose.  After the black tank is drained you will follow-up and drain the gray water tank and that acts as a flush for the hose and washes most of the material down into the sewer pipe.  To drain the tanks all you have to do is pull, not twist the handle, but pull the T-handle that is for your black water tank.  Start out slow and watch for any leaks in the hose and fittings.  Once you are confident there are no leaks open the valve to allow any solids to flow out past the valve and into the hose.  Watch the progress in the clear pipe extension and close the black water tank when the flow stops.  Now open the gray water valve in the same manner.  Since we have already determined there are no leaks, open the valve all the way and let that water flush and rinse the solids from the hose into the sewer.  When both tanks are drained, close the valves and you are done.  Not so bad, my biggest fear each time is that there will be a leak and make an embarrassing and stink mess, but so far so good!

The purpose of leaving the valves closed unless draining the tanks, even when parked at a campsite,  is you want to always keep some water in the black water tank to keep things from drying out and crusting up in the bottom of the tank and on the level sensor( that’s another experience and story for another time), and you want to gather as much gray water as possible to act as the flushing water for the hose after draining the black water, really pretty simple and basic once someone explains it all…I hope we have helped ease some anxieties of draining those tanks.

Feel free to leave any other helpful thoughts or ideas in relation to thet waste tanks, the more input, the better informed we will all be

P.S. and don’t forget to throw a black water/waste tank deodorizer with beneficial bacteria down the toilet after you drain the tanks and with your first flush.  After draining, I like to go in the trailer and throw a deodorizer packet in the toilet, flush the toilet and then keep the water running for a little bit to get a few gallons into the bottom of the tank.

Happy Camping!!

Tom & Tracie

This following video shows a perfect example of all the written procedures above.  Watch the video and it will all come together and make sense.

Video credit : YouTube channel – RVGEEKS



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