Shower backing up in 2017 Roadtrek Simplicity SRT
I have a brand new 2017 Roadtrek Simplicity SRT and I'm running into an issue with the gray water system. According to the specs, the gray water tank is 22.8 gallons. But if we dump the tanks, use some water for washing hands and dishes and take 2 quick showers, the shower drain starts backing up. This of course would indicate the gray water tank is full, but this is happening far sooner than I would expect.
Before this I had a 1999 Roadtrek 190 Popular with a 25 gallon gray water tank and we could do the same amount of dish washing and at least 2 showers and still have plenty of room left in the tank. I realize that the new gray tank is a little smaller but it's not small enough to account for this issue.
The backup can happen as quickly as 3 days after dumping with this RV. With the old RV I could go closer to a week with 2 people. We aren't taking long showers so between minimal dishwashing and the quick showers I can't imagine we are using 22+ gallons so fast. The other day the shower backed up only 2 days after dumping and only 1 shower and dishwashing.
The fresh water tank holds 37 gallons, so to fill up the 22.8 gallon gray tank we'd have to use almost 2/3 of the fresh water. But between dishwashing, showers, the toilet, cooking, and drinking water, the fresh tank still has plenty in it after a few days. Our water tank is still 2/3 full when the backups start happening. We certainly aren't using over 22 gallons in just a few days. We aren't using the RV much differently than the old RV in terms of how we use the water.
I realize the tank levels aren't particularly accurate, but the gray water level reads 2/3 when it's backup up into the shower, and after dumping it's usually still reading 1/3. After driving around a bit it'll sometimes go back down to empty but quickly it will go back to 1/3. I never had issues with the gray water levels being that out of whack in my old RV but maybe there's something wacky with them in this RV.
Obviously it just sounds like the gray tank is full, but I find it hard to believe that we're using that much water so quickly, especially since I had my old RV for a year and used it in the same way with no issues like this. I've made sure to dump the tanks completely, using the macerator pump and then the gravity dump hose to make sure there wasn't anything left in the tank.
It's under warranty of course but my service appointment isn't for a couple weeks and that may only be a diagnosis. I called Roadtrek customer service and they didn't know anything about this issue. We're in the RV full time in September and this is a big pain.
It almost seems like there is an obstruction in the gray tank that is preventing it from filling to its capacity, or a venting issue that is trapping air in the gray tank, or the gray tank is much smaller than advertised.
If anyone has any ideas that I could look into I'd love to hear them! If I can find a place to do it, I will try filling the gray tank 1 gallon at a time and see when the shower starts backing up, so at least I will have something measurable with this problem.