Forum Discussion

mlts22's avatar
mlts22
Explorer II
Nov 15, 2013

Evaporation and black tanks...

In April, I "summerized" my TT (poured 5-10 gallons of water in black and grey tanks after a crushed ice treatment, then completely rinsing and flushing the insides out.)

Last weekend, during the winterizing process, I hooked up my macerator pump to empty both tanks in preparation to add antifreeze. The grey tank was bone dry, the black tank had about a liter of water in it at most. Thankfully they were well cleaned out, so the "son of a poop pyramid" was not an issue.

Just a warning to people... if one forgets to empty a black tank, it might just "empty" itself in a very unexpected way, if one isn't prepared for it.
Seeking Advice

9 Replies

  • John_Joey's avatar
    John_Joey
    Explorer
    Nov 16, 2013
    Go to WalMart and buy a $20 clear flush king with a valve. Put it on the end of the line with the valve shut and see what you got in 48 hours. I'm guessing you got a leaking valves.

    If that isn't the case, you now have a flush king to use in the future to clean the tanks with.
  • Dog_Folks's avatar
    Dog_Folks
    Explorer II
    Nov 16, 2013
    fla-gypsy wrote:
    Dog Folks wrote:
    fla-gypsy wrote:
    How can water evaporate from a sealed container with a closed valve? I find that highly unlikely. Do you have any other theory other than evaporation?


    It is not sealed. It has a vent pipe through the roof.


    I understand the vents but I got to tell you I still think that is highly unlikely considering the amount of water they said they added. I have never experienced anything like that sort of evaporation.


    In theory, I agree with you. IF the amount of water the OP says was put in, and there are no slow leaks, I cannot think of any other way.

    But then again, I'm not that smart. LOL
  • dcason's avatar
    dcason
    Explorer
    Nov 15, 2013
    You also need to keep the seal moistened (some water/antifreeze in the bowl to keep seal operating nicely and not leaking fumes).
    Donna
  • fla-gypsy's avatar
    fla-gypsy
    Explorer
    Nov 15, 2013
    Dog Folks wrote:
    fla-gypsy wrote:
    How can water evaporate from a sealed container with a closed valve? I find that highly unlikely. Do you have any other theory other than evaporation?


    It is not sealed. It has a vent pipe through the roof.


    I understand the vents but I got to tell you I still think that is highly unlikely considering the amount of water they said they added. I have never experienced anything like that sort of evaporation.
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Nov 15, 2013
    April you 'summerized'and Nov you 'winterized'.....water you left in tanks evaporated between April & Nov?

    You need to use that RV more frequently :B

    If leaving RV unused for extended periods.......pour some RV anti-freeze into tanks. Even in summer time. The RV anti-freeze will not evaporate as quickly and the tank bottoms and dump valve seals will stay wet.

    Even after a through cleaning there is still some stuff left behind due to the tank design and lip in side of tank below the drain line.
    Best to not let them dry out.
  • mlts22's avatar
    mlts22
    Explorer II
    Nov 15, 2013
    Both my black and grey tanks have decent roof vents. If not, the smell would wind up in the rig.
  • Dog_Folks's avatar
    Dog_Folks
    Explorer II
    Nov 15, 2013
    fla-gypsy wrote:
    How can water evaporate from a sealed container with a closed valve? I find that highly unlikely. Do you have any other theory other than evaporation?


    It is not sealed. It has a vent pipe through the roof.
  • fla-gypsy's avatar
    fla-gypsy
    Explorer
    Nov 15, 2013
    How can water evaporate from a sealed container with a closed valve? I find that highly unlikely. Do you have any other theory other than evaporation?

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