Cab we use rock salt in RV holding tanks for freezing?

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Praful naik

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Jun 18, 2021
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texas
I started watching RV vlogs and was fascinated by the travel experience! I'm new to RVing and was checking some of the queries!

Can we add rock salt to the holding tanks for freezing and if yes, then how does it work?

Can we add rock salt to the fresh water tank?

Is there any drawback to this?

What about the other options for keeping the holding tanks warm while traveling in winter?

Anyone who can answer them in detail! Thanks

 

John From Detroit

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Davison Michigan
To the black tanks Rock salt or even table salt will reduce the freezing point of water a few degrees like 25 if you add enough of it. NOTE 32 (f) is the freezing point of PURE water. what's in the black tank,,,, a long way from pure (I do not know the freezing point)

Fresh tank ..Have you ever drank salt water.. (YUCK)
 

Praful naik

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Jun 18, 2021
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texas
Is there any standard for using rock salt for using it as antifreeze? I have seen a lot of people telling in the forums not to go with rock salt as it can be corrosive
 

jackiemac

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Hi and welcome to the forum. Good to have you join us.

There's no such thing as a stupid question, so please ask anything you need to.

I've never heard of putting salt in a tank and not sure why you would as anti freeze works well, or leaving tank empty.
 

TheBar

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MS
Corrosion of the metal parts and sensors in the tank and dump valves could definitely be an issue. Rock salt is a crystal with sharp edges. Undissolved crystals might slice up the rubber seals in the dump valves.
 

Lou Schneider

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No need to use rock salt when you can get drinking water safe RV antifreeze for a few bucks a gallon. Either drain and blow out your freshwater system or run a gallon or two through it.

Waste tanks are rarely a freezing problem except for not being able to drain them if they freeze over. Any ice that may form has plenty of room to expand without damaging anything.
 

Gary RV_Wizard

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What Lou said. Potable water antifreeze is cheap, probably no more expensive than rock salt, and doesn't corrode or leave nasty residue behind. And unless they are full, waste tanks are rarely freeze damaged - you just have to wait for them to thaw to be dumped.

But yes, you could add rock salt to the waste tanks and get some degree of anti-freeze protection. The popular Halite brand rock salt it is just impure table salt (sodium chloride) but some "rock salt" products may contain calcium or potassium chloride. I wouldn't want any of those in my fresh tank.
 

Matt_C

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Mar 4, 2019
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SE - Mich
Praful naik,
You have asked about three very different questions. I will try to field them as I see them.
1- There is no good reason to need rock salt around an RV except for traction.
2- The contents of a black tank are largely freeze proof as they are - assuming you are not using too much water.... Did you know that many salt-poor or corrosion sensitive places use urea to de-ice. It has a very good freezing point suppression, it is just more expensive than rock salt.
3- Most RVs have the potable tank inside the living space, so if you aren't freezing, neither is your water. Some RVs unfortunately do have water lines in unheated spaces and have had individual water lines freeze, but salt in the potable tank is not a good way to deal with this. A an associate has suggested that filling the potable system with a mix of vodka and water could eliminate this issue. (And maybe others.)
Matt
 

donn

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Nov 8, 2009
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Why would you want to use salt? Many parks are on septic systems. Anything other than normal waste can disrupt normal septic system function creating a big mess for the park.
 

Praful naik

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Joined
Jun 18, 2021
Posts
7
Location
texas
Hi and welcome to the forum. Good to have you join us.

There's no such thing as a stupid question, so please ask anything you need to.

I've never heard of putting salt in a tank and not sure why you would as anti freeze works well, or leaving tank empty.
Great community! 🤝
 

decaturbob

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Joined
Oct 31, 2015
Posts
484
Location
central Illinois
I started watching RV vlogs and was fascinated by the travel experience! I'm new to RVing and was checking some of the queries!

Can we add rock salt to the holding tanks for freezing and if yes, then how does it work?

Can we add rock salt to the fresh water tank?

Is there any drawback to this?

What about the other options for keeping the holding tanks warm while traveling in winter?

Anyone who can answer them in detail! Thanks
we have RV antifreeze. Rock salt? No way
 
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