Can the Valterra Twist-On Valve # T58 Be Used as a Secondary Gray Tank Valve?

Updated 02/19/2026 | Published 02/11/2026

Question:

We are stationary for five months. To limit the weekly chore of crawling under my slide to empty the gallery grey tank I was thinking about adding a sewer hose to the tank outlet, leaving the handle open and installing T58 at the end of the hose where it connects to the Y valve. This way I can open the waste valve at the clear Y connection and not have to crawl under the slide. Will the T58 work in this situation? Is it stable enough to hold back the kitchen sink waste until pulling the handle. Thanks.

asked by: Gregg J

Expert Reply:

Hello Gregg,

Great question!

Yes, the Valterra Waste Valve for RV Black Water Tank - Twist On - 3" Bayonet Hooks to 3" Lug # T58 will work well for your setup.

The # T58 installs directly onto your existing 3-inch bayonet termination, allowing you to leave your kitchen (galley) tank valve open while adding an external shutoff point at the end of your sewer hose. You would attach your sewer hose to the outlet of the T58, keep the T58 valve closed, and then simply pull that handle when you’re ready to drain. This eliminates the need to crawl under the slide each time.

The # T58 is designed specifically for this type of application. Per Valterra, the valve is rated to hold back up to 15 psi, which is more than sufficient for normal gray water head pressure from a kitchen tank. Under typical RV conditions, gray water systems are gravity-drain and do not build pressure anywhere near that level, so it will securely hold back the kitchen wastewater until you pull the handle.

As long as the bayonet connections are fully seated and locked, the seals are in good condition, and the hose connection is secure, you should have a stable, leak-free setup. One of the main benefits of the # T58 is that it gives you an external control point without requiring any modifications to your existing plumbing.

Where are you staying for 5 months, and where are you headed after? My Dad is a full time RVer, he is currently in California for the cold months and is starting to get the itch to hit the road again.

expert reply by: Kate F

Gregg J.

2/17/2026

Thanks Kate for your help. While we're not full time, we spend five summer months camp hosting for Colorado Parks and Wildlife. We then return home to NC before spending two winter months camping in myrtle Beach.

Kate F.

2/18/2026

@GreggJ Being a camp host sounds like an awesome time! I am sure you hear lots of stories and meet some interesting folks =) I grew up on the West Coast, would love to visit the East Coast beaches one day. Thanks for sharing, and safe travels.

Bob

2/18/2026

We used this waste valve for a different reason. The RV manufacturer coiled the cable to open and close the primary valve and it was sticky and stubborn and quite a ways from the end of the waste pipe. I wanted a quick and easy way to stop the flow if something happened when emptying the tank. For example, I have accidentally missed one of the tabs on the bayonet fitting leading to a spill. I have also had the hose pop out of the hole. Nice to be able to easily and quickly stop the flow.

Kate F.

2/19/2026

@Bob Sounds like a mess I do not want to deal with. Thanks for the response Bob, very helpful =)

Camp J.

2/18/2026

The T58 should be able to do that. I would work to sure there is about zero food waste through the sink to avoid settling in the flex line before the valve. You could also upgrade the gate valve under your slide with a remote operated version like a VAL54 or similar. Just mount the actuator handle outside the slide width. Good luck with whatever you chose.

Millard

2/18/2026

The Valterra valve works well for flushing out my black tank because I need to leave the interior valve open but keep the water in while it fills up. But I have noticed over time it has begun to drip under pressure of releasing all 45 gallons at once. It is fine when just holding back the water in the pipe.