black tank valve


New Member
i am very new and just flushed system from antifreeze, i pulled the grey and black valve, but my question is, how do I know if these valves are open or closed. they don't seem to push back in. :(

also, what is an inline filter for water hose? i had low water pressure. wasn't sure if i needed water pump on or off, i used hose hooked up and left it on. i was told to take all filters off shower and sink faucets and use an inline filter on hose? is this correct and is that what i ask for, "inline" filter? also do u think i need a plug in voltage meter to keep an eye on my amps. is it true, it shouldn't go below 105, if it does, do i turn off something, like air cond.


Senior Member
Re: black tank valve

The waste tank dump valves should be quite easy to see if they are open of closed. When open, there is several inches of shiny metal shaft that shows between the valve handle and the valve body. When the valves are closed there will be almost no metal shaft showing.

Any good RV supply store will sell water filters. The "in line" type are disposable filters that screw to your water hose and they usually also have a short length of hose with them to connect to the hydrant. There are no filters on the shower or faucets unless someone added them but they do come with flow restricters on all of them which were put there to save water. They save it by restricting the flow. You can easily find them by removing the shower head and find a disc under it that has small holes for the water. Remove it. Next unscrew the end from each faucet and you will probably find one of those same discs in each one. Remove them also.

A volt meter is a good thing, but the cheap "plug-in" type are nearly useless. They just are not accurate. Spend about $30 at any home supply store and you can get a digital one that will actually tell you something useful. A volt meter will not tell you how many amps you are using and an amp meter that could would be rather costly and probably of little use. What you are concerned about is poor voltage which can cause problems for the 120V-ac motors, particularly in your air conditioners. If you run the motors when voltage falls below 108V it will damage them. By 105V they will likely burn out if run for an extended period. Your best bet is to not use the power from any park where the voltage is less than 110V since voltage can vary and I doubt that you would be willing to spend all of your time sitting and watching a meter! The best way to protect your RV is by using a line monitoring device such as those sold by Surge Guard.

DL Rupper

Senior Member
Re: black tank valve

Better yet coolnana5, if the Park/shore voltage is consistently low (below 105 V) use a Autoformer. It will boost the low voltage to an acceptable level (110+V) and you can continue to use your air conditioner or other high voltage appliance. The Autoformer is pricey ($375 30 amp, $475 50 amp), but well worth the cost. A surge protector will only shut your 120 V ac voltage off if it goes into an unacceptable level. Shutting your voltage off does not rectify the problem. The Autoformer does fix the problem.

I do use the plug-in type voltage meter so I can determine at a glance if the voltage is in the green zone (above 105 V). In most RV Parks the voltage fluctuates at different times of the day. When everyone is using a air conditioner or an electric heater it tends to go low. I have found when I operate my air conditioner my voltage drops and I can determine that with a glance at my plug-in volt meter. I do have a digital volt meter that I occasionally double check the accuracy of my plug-in meter. The plug-in has been very accurate. If you only have the digital volt meter, you may not know when your voltage drops to a dangerous low voltage point. Or if you have a surge protector and your voltage shuts off, you will have to turn off your high voltage appliances. Could get hot in the summertime or cold in the winter. :laugh: Also, not all surge protectors shut your voltage off when it drops too low.