Full Tank Assumptions - 2023 Bay Star?

[stevenapril]

I'm assuming if I accidentally overfill my fresh water tank there is a pressure relief valve that will simply dump the extra water.... is this an accurate assumption?

How about the Grey and Black tanks.... I'm assuming that those don't have a relief valve as you cant dump on the ground... so I bet they backup into the toilet (for Black) and into the sink/shower for the gray tank. Is this accurate?

[Wa2fast]

I had a Canyon Star which is the same basic chassis as the Bay Star.

The fresh tank has an overflow on the top that allows excess water to flow out. I experienced this in person with my coach when I was sanitizing the tank prior to our first trip. No backup inside, or overflow anywhere into the coach...just out onto the ground.

Our gray tank backed up into the shower if we left it too long before dumping. Never left it beyond that point to see where it would overflow into.

Black tank...never experienced any overfull / overflow as we kept a close eye on things. But there was a vent / one way valve under the bathroom sink, just under the countertop which we could smell from time to time.

Hope that helps.

[l1v3fr33ord1]

stevenapril-

Have not owned a Newmar. But, these details are similar across many coaches.

As others have said:

Fresh water tank- should go out the overflow. The overflow outlet should be under the coach near the tank.

Grey water tank- Should back up into shower pan. Block that off, then it will come out the sink drains and/or clothes washer drain (if you have a clothes washer). Block those off and grey water will come out the roof vent.

Not mentioned yet:

Fresh water tank- Fill carefully until you ensure the overflow works and also know about how many gallons it takes, as it's possible to split a tank by over-pressurizing it. Some coaches have overflow piping that doesn't work well, including having a habit of creating a siphon that will drain the water from the tank after you shut off the fill flow. Another reason to be careful.

Black water tank- Out the roof vent, if the check valve under the bathroom sink works correctly. If not, out the check valve. Will not likely appear at the toilet-floor joint. Note: If you suspect you have overfilled the black tank, DO NOT open the toilet flush valve! Instead, dump the tank's contents first. If you open the toilet flush with the black tank full you will likely create a geyser in the bathroom, the contents of which are... unpleasant.

[Rescar]

Steve and April,


There IS an overflow valve on the fresh water tank which will vent automatically if overfilled (or near full and on a slope). Grey and black tanks have no such vent. On my 2018 Bay Star, when the black tank is near full, the grey tank is also nearing full (unless I lose track of showers and extra uses)... normally 3-4 days. Grey tank will back up into your shower through the 'p' trap and you'll smell that you need to pull the tank (grey water stinks worse than black)! Black tank will shower your behind when you try to flush if you're not paying attention. ALWAYS drain black tank first, then flush with grey water (keeps your hoses cleaner as well as downstream parts). Do NOT leave either black or grey valves open full time, even if you're connected in a campground if you want to avoid the "poop pyramid."

[NCC-1701A]

IMO the fresh water overflow works a little too well!!! If you experience what many have reported, you'll be dumping water out on every turn and slope! :-)

[Dennis C.]

On my coach the fresh water overflow is underneath the coach on the curb side/passengers’ side, just in front of the rear axle. I’ve had a few unexpected water dumps when parking on unlevel ground with a full tank. It’s not very much water, but it’s always a surprise when you step out of your coach and there’s water running on the ground!

[Old-Biscuit]

Fresh water tanks have an overflow ....open ended pipe from top of tank and thru bottom of RV so when it overflows you will notice water running out underneath RV

Can have siphoning effect when tank is FULL
Simple 1/8" hole in pipe at tank will stop siphoning

Waste tanks do NOT have overflows.....environmental issues
Black will backup into toilet line then burps when you try to flush
Grey will typically backup into shower

[DustyDriver]

Wa2fast: The “check valve” under the bathroom counter is the antisiphon valve for your backflush line to the black tank. That is what prevents fluid from the black tank backing up into your garden hose when you’re finished rinsing the tank and go to turn off the spigot.

BTW. I knew one fellow who was back flushing his black tank and lost track of how much time he had had the water flowing. He ended up having a very nasty volcano-like fluid eruption out of his black tank vent pipe up on the roof!

DD