Black Water Tank – The design of a great waste tank

Black water holding tanks are a key aspect of boondock camping, or otherwise where sewer hookup is simply not available. A black water tank is designed to hold, and facilitate the draining, of solid and liquid wastes from a toilet.

Here at ICON, we took a look at what makes a useful and durable RV black water tank.

Black Water Tank Key Considerations

Holding Capacity

You want a black water tank that has an appropriate capacity for your use. Usually, the more people you expect to use the washroom in your RV, the more capacity you will need for waste. Conversely, if you aren’t expecting to use it much, a small tank may be appropriate to keep weight down and conserve space. Tanks provided by ICON come in a variety of sizes to make getting the right capacity easy.


If there’s one thing you absolutely don’t want, it’s a busted or leaking waste tank. At ICON, we take tank durability seriously. Holding tanks are constructed of high impact ABS, with solvent welded seams. By the time we are done, any seam or fitting has become one with the tank. That makes for a durable construction!


A tank has to slope towards a pre-designated point to be effective at draining. You want to be able to drain & flush the wastes out as effectively as possible. That’s why ICON has a variety of drain locations in their designs and channels embossed in the bottom to promote clean drainage & flushing.

Side Drain Black Water Tank

Side Drain Black Water Tank

Flexible Intake Position

The intakes are best installed according to where your plumbing goes through the floor. So having the flexibility to insert the intakes as necessary is crucial for an aftermarket replacement. The majority of ICON tanks have a flat top face, facilitating the installation of any intake or vent, anywhere on the tank!

Installed Intake Fittings

Installed Intake Fittings

Mounting Flanges

The tank must have a robust flange to help you mount it to the underside of your RV. That goes back to our solvent welded flanges. They are thick and robust for use in mounting the tank. You can use them to slide the whole tank onto a rail/angle iron, or you can pre-drill and mount with screws/bolts into the floorboards.


There you have it. Waste tanks are an important part of your plumbing in an RV and ICON has your back with the best tanks & accessories around.

Take a look at all ICON Black Water Tanks >>Click here.



9 Responses to “Black Water Tank – The design of a great waste tank”

  1. Dan Asbjornsen

    Hello from Dan.
    my tank is directly under the toilet.
    My question is:
    How far into the tank should the “fill tube” protrude into the tank.?
    Mine is almost all the way to the bottom of the tank. about 1″ from bottom of the tank.
    This seems to be a problem as it does not allow any of the debris to move out of the fill tube and after just a few uses, when flushed , it causes the tank to “burp” up into the toilet bowl. the bowl being full of water, splashes all over the walls etc.. nice…
    this is in a brand new travel trailer..

    • icondirect

      Hey Dan,

      I shouldn’t think that the “intake” from the toilet should not protrude that far into the tank. We usually recommend this fitting for the toilet intake. You can see on that page that the fitting does not protrude downwards very far at all, it just has enough to it to allow the 3″ male from a toilet flange to be threaded into it.

      It sounds like you may need to investigate replacing at least the intake fitting. This may be possible by cutting out the existing fitting and gluing in a new one, however that may prove difficult. A whole new tank may be necessary – without knowing further details.

      Give us a call 1-888-362-4266 to discuss further.


  2. direct papers

    The characteristics of the tanks of this type are important for a further operation. We should pay attention to their resistance during the use.

  3. Dan Asbjornsen

    Hello from Dan.
    Sorry for the long time update.
    I called the dealer, and explained the issue.
    they asked me to bring the trailer in.
    They resolved the issue by shortening the tube as I asked.
    This seems to have resolved the problem.
    Perhaps a mfg production issue.
    I would imagine that if 8 or 9 got out of production like this
    they would be getting calls about the problem.
    and some bad press.
    so, thank you to my dealer, for quickly resolving the issue with no argument.
    Dan. Asbjornsen.

  4. Lee Getzinger

    I plan to run a aluminum angle metal all around underneath the mounting flange of my new Icon black tank. I then was going to drill holes thru the angle iron and the flange and bolt to the bottom of my RV (new install). Will this weaken the flange of the tank if it is completely supported underneath by the angle iron?
    Thank you
    (Mounting tanks under bottom of a pontoon boat)


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