Keeping Gray Water Tanks from Freezing During Winter Usage

[cjmorin]

Hello, friends!

My girlfriend and I have owned our 1998 Blue Bird All American RE for about a month now. It was almost entirely built out by the previous owner and I have some questions regarding his plumbing configuration and how it applies to our planned full time usage this winter. First, some system basics:

- 65 gal plastic fresh water tank in the living compartment underneath the bed located in the rear of the vehicle. It is right next to the engine-hump and is relatively well insulated.

- 35 gal plastic gray water tank located in the rear undercarriage storage bay directly beneath the shower. The shower pan has a short run of PVC pipe that protrudes down from the drain, transitioning to flexible drain hose that forms an "S" to the tank.

- 25 gal plastic gray water tank located in the front undercarriage storage bay beneath the kitchen sink. Same configuration here, except the PVC run is slightly longer and goes at a diagonal from the sink before passing through the floor.

The storage bay is unheated, and I am concerned about gray water freezing solid during the winter! We are located in Western MA and temps routinely go down to 10-20° F from Dec to March. I have some theories about how to prepare for this:

- Adding 20-40lbs of driveway ice melt into the gray water tanks immediately after draining and preparing to refill them. Gray water would mix with the salt, forming a high concentration brine that would freeze at a significantly lower temperature than plain water. As this product is routinely used on the streets, I imagine it must be safe for plants/animals/water table, and should be ok for all gray water dump locations.

- After shower or sink usage, pouring a small amount of concentrated marine grade PG or EG based antifreeze down the drain, to resist freezing in the "S" of the plumbing. I believe that this S is integral to the design, to inhibit smells from wafting back up from the tanks. If this is not required, then I will redo the connection and eliminate the "S" altogether. Please note that no food waste ever goes into gray water so I don't know what to expect for smells from soapy body wash rinsate.

We will not have a reliable shore power connection, and so tank jackets or heating rods are impractical.

Looking forward to hearing some people's recommendations and experience!

Chris

[Njsurf73]

Salt is not good in any tank that may dump to a septic system... It will kill plants in high enough concentration... And it will play havoc on any metal parts..
Heating the tanks is the best option... Short of that I would think uber-insulate them and keep an eye on them.

Originally Posted by cjmorin

Hello, friends!

My girlfriend and I have owned our 1998 Blue Bird All American RE for about a month now. It was almost entirely built out by the previous owner and I have some questions regarding his plumbing configuration and how it applies to our planned full time usage this winter. First, some system basics:

- 65 gal plastic fresh water tank in the living compartment underneath the bed located in the rear of the vehicle. It is right next to the engine-hump and is relatively well insulated.

- 35 gal plastic gray water tank located in the rear undercarriage storage bay directly beneath the shower. The shower pan has a short run of PVC pipe that protrudes down from the drain, transitioning to flexible drain hose that forms an "S" to the tank.

- 25 gal plastic gray water tank located in the front undercarriage storage bay beneath the kitchen sink. Same configuration here, except the PVC run is slightly longer and goes at a diagonal from the sink before passing through the floor.

The storage bay is unheated, and I am concerned about gray water freezing solid during the winter! We are located in Western MA and temps routinely go down to 10-20° F from Dec to March. I have some theories about how to prepare for this:

- Adding 20-40lbs of driveway ice melt into the gray water tanks immediately after draining and preparing to refill them. Gray water would mix with the salt, forming a high concentration brine that would freeze at a significantly lower temperature than plain water. As this product is routinely used on the streets, I imagine it must be safe for plants/animals/water table, and should be ok for all gray water dump locations.

- After shower or sink usage, pouring a small amount of concentrated marine grade PG or EG based antifreeze down the drain, to resist freezing in the "S" of the plumbing. I believe that this S is integral to the design, to inhibit smells from wafting back up from the tanks. If this is not required, then I will redo the connection and eliminate the "S" altogether. Please note that no food waste ever goes into gray water so I don't know what to expect for smells from soapy body wash rinsate.

We will not have a reliable shore power connection, and so tank jackets or heating rods are impractical.

Looking forward to hearing some people's recommendations and experience!

Chris

[cjmorin]

Thanks for your feedback.

The location that we are planning to park has access to a direct sewer dump, so I don't think we will have to worry about septic. It does not have to be let out into the ground to affect plants or animals. Regarding it's effect on metal, point taken, but I do not believe that it will ever come in contact with any metal if the crystalline salt is poured directly into a plastic gray water tote. There is minimal metal in the water lines already, but that should keep it pretty much segregated from all things.

I do not believe we will be able to heat or jacket the totes.

[CaptSquid]

You might consider an electric heating pad https://www.etrailer.com/RV-Fresh-Wa...77-000164.html

[turf]

i use the heating pads from etrailer and they are ok. timing is everything.

i have them hooked to my battery. a day or 2 before dumping i'll plug it into the battery. if you get above freezing during the day, its best to dump then.

i;ll add a bit of rv antifreeze first into the tank after i dump it to help lower the freezing point of the waste water to come. adding after it is frozen does not help.

the pads run a pretty low load so don't expect it to thaw a poopsicle in any record time.

timing is everything.

one of my pads needs replacing after 1 season use. it de-laminated and came apart. still worth the money.