RV waste valve replacement is not something any RVer wants to think about. But occasionally, it becomes necessary. Fortunately, it’s a relatively easy repair, especially if you have a guide to follow.
This post outlines the steps for the DIY replacement of a black or gray waste valve. Not only are we giving you a step-by-step guide, but we’ll also provide a video for those who prefer to learn visually. Let’s get right to replacing a waste valve on an RV!
- 1) What Are the Symptoms of a Failing Gray or Black Waste Valve?
- 2) Where Are the Gray and Black Waste Valves Located on My RV?
How to Replace an RV Waste Valve
- 3.1) Gather the Items You’ll Need for the Job
- 3.2) Empty the Black and Gray Tanks
- 3.3) Loosen the 4 Bolts that Hold the Old Waste Valve in Place
- 3.4) Remove the Old Waste Valve
- 3.5) Remove the Old Rubber Gaskets and Set the New Gaskets in Place
- 3.6) Set the New Waste Valve in Place
- 3.7) Install the 4 New Nuts and Bolts
- 4) Watch Our RV Waste Valve Replacement Video
- 5) Free RVing Tips, Tricks, Reviews & Giveaways
What Are the Symptoms of a Failing Gray or Black Waste Valve?
A couple of different symptoms may arise to indicate that you’ve got a failing waste valve.
- There is an occasional small drip from the handle (primarily when pulling it for dumping).
- Even though both valves are closed, a small amount of water accumulates behind the sewer pipe cap. You’ll notice some liquid when you open the sewer pipe cap before opening either your gray or black valve.
Note that the black and gray waste valves (sometimes called gate valves or blade valves) should seal completely so that no liquid is found when you open the main sewer pipe cap. If you have liquid present there, or if you see liquid dripping from the handle when you pull it to dump your tanks, your gray or black waste valve is not sealing anymore.
The easiest way to tell which valve is leaking is to use the sniff test. Gray water smells bad, but it doesn’t have the same sewage smell that liquid from the black tank does. Also, fluid from the black tank is likely to be darker (generally brown), while liquid from the gray tank should be lighter and more grayish.
So, you’ll need to use your nose and eyes to determine which waste valve needs replacing. Note that the steps for black tank valve replacement will be the same as the steps for gray tank waste valve replacement.
Where Are the Gray and Black Waste Valves Located on My RV?
On many motorhomes, the valves are installed right inside the water bay (so the handles are the standard handles that come on the black and gray valves without the need for extensions). On many other RVs, the valves are mounted just below the bodywork on the street/driver’s side, with the handles visible.
On other RVs (often travel trailers, fifth wheels, and even smaller motorhomes), the waste valves may be mounted further inboard… up and under the RV (and this can include being placed up above anything used to enclose the bottom of the trailer for better insulation, so this may need to be cut/removed for access). The manufacturer then installs an extension handle (in some cases, it’s a solid extension, and in others, it’s a flexible cable extension) to bring the pull handle out toward the edge of the RV for easier reach.
With this type of remote valve placement, there will be a couple of extra steps to replace the valve completely. So, if your RV is equipped with an extension, you’ll need to unscrew it from the waste valve and then remove the valve handle from the new replacement waste valve, and re-attach the extension once the job is done and the new waste valve is seated correctly and in place.
How to Replace an RV Waste Valve
Again, the following procedure will work for the gray or black water dump valve.
NOTE: in most RVs, the gray tank valve is likely to be a 1 ½” valve (because only liquids drain from that tank). The black tank valve will be a 3” valve (for solids to drain out). However, some RVs use a 3” valve for both, and there are also instances where one or the other of the two valves will be a 2” valve. For these reasons, it’s important to confirm which size you need before ordering and/or removing the failed valve.
Gather the Items You’ll Need for the Job
- Rubber gloves
- Appropriate size box or open-end wrench
- Socket wrench/ratchet and appropriate size socket
We like the 3/8″ Dr. Spin Disk Ratchet Handle because it includes a “Spin Disk” that allows you to use your fingers to tighten and loosen nuts or bolts when there isn’t enough room to move the ratchet handle (very handy in tight spaces like RV water bays!).
- 3/8" Dr. & bits 2-in-1 thumb ratchet
- Spin disk on ratchet head for one-finger spin-down/off
- Sponge and/or paper towels to absorb or wipe up any drippage (whatever you use, you’ll want to throw it away!)
- Replacement gate valve (any of the following may be appropriate for your situation):
Valterra 1-1/2″ Waste Valve with Metal Handle (Gray Tank)
- Bladex waste valve.Fit Type: Universal Fit
- Use with GrenTec, Bladex, Valterra, Bristol, and Anonda valves
Valterra 3” Waste Valve with Metal Handle (Black Tank)
This one is like the one on our motorhome, where the blade valve is installed between two sections of plumbing, and there’s a separate piece further downstream toward the opening that acts as the attachment point for a sewer hose.
- NO MESS: At-home RV body valve repair is mess-free for your convenience
- VERSATILE: Bladex valve is compatible with GrenTec, Blade, Valterra, Bristol, and Anonda valves
However, if yours has the bayonet fittings right on the valve body, you’ll need to use this one instead:
Valterra 3″ Valve Body with/Cap
- THIS IS NOT A TWIST ON STYLE - This has a 3" Hub o the reverse side which is a glue on style.
- GLUE ON Waste valve with 3" cap
Only in rare cases would the following product be the right choice, but we want to supply a link in case yours is this size (again, note that the 1.5” or 3” gate valves are far more common).
Valterra 2″ Waste Valve with Metal Handle
- Bladex waste valve
- Use with GrenTec, Bladex, Valterra, Bristol, and Anonda valves
Finally, many RV owners also find the following product very helpful. It can be used as a secondary blade valve, attached at the outlet where you’d usually attach your sewer hose, as a stopgap measure to keep tank contents from leaking until you can permanently repair it. Or it can be used as a failsafe, so there are always two gate valves between the tank(s) and the outlet.
Valterra T58 Twist-On Waste Valve
- No more mess with an old valve problem.Fit Type: Universal Fit
- Twists onto your current waste valve
Empty the Black and Gray Tanks
PRO TIP: If possible, perform the waste valve replacement when you have the RV tilted away from the side of the tank that the valve is on to help ensure that any remaining contents in the tank don’t leak out while you’re working.
This may also help if you have to replace the tank valve without being able to dump the tank(s) first. For example, this could be the case if the blade valve fails in the closed position and won’t open. In this case, you may need to tilt the RV more significantly to keep tank contents from escaping when removing the valve. Either way, have a bucket handy!
Loosen the 4 Bolts that Hold the Old Waste Valve in Place
With the closed end of a box wrench holding the nut in place, use your socket wrench to loosen the four bolts on the body of the old valve.
Remove the Old Waste Valve
Gently flex both sides of the drain plumbing to allow the blade valve body to be removed from between them. You can use your sponge or paper towel to clean up any dripping.
Remove the Old Rubber Gaskets and Set the New Gaskets in Place
Remove the old gaskets/rubber seals from each side of the open drain pipe. They may be stuck on either side or to the old valve body. Please make sure you locate them before proceeding so you know they’re not still stuck in place.
Open your new waste valve and set the new gaskets in place on either side of the blade. Alternatively, you can set the new gaskets in place on either end of the drain pipe before installing the new waste valve. Either way works. The most important part is to ensure the new gaskets/seals remain perfectly in place and don’t get twisted/pinched as you replace the waste valve.
Set the New Waste Valve in Place
Being careful to keep the new gaskets in place and not pinched, gently pry the two sides of the drain pipe apart to give yourself room to set the new waste valve in place. Line up both ends of the drain pipe and the body of the new waste valve so that the holes for the bolts align correctly.
Install the 4 New Nuts and Bolts
Install the four new nuts and bolts using your box wrench and socket/ratchet. Ensure the new seals/gaskets remain perfectly in place and all pieces align so the bolts slide in easily and can be properly tightened.
Tighten each of the four nuts/bolts only loosely until all four bolts are in place and everything is aligned. Then, tighten down the nuts/bolts.
That’s it! Mission accomplished! Your new waste valve is installed.
Watch Our RV Waste Valve Replacement Video
To follow us as we install a new gray waste valve on our motorhome, check out our YouTube video and follow us step-by-step:
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