A properly working RV waste dump valve should not leak and should be easy to operate. If you have a waste valve that leaks even a little, or the gate doesn’t open and close with ease then it’s time to replace it. Don’t wait… it won’t get better and as it gets worse the replacement may get more difficult.
Also, if you have a hard-to-reach waste valve you may want to consider may want to consider installing an electrically operated waste valve. Although installing the wiring and switch will require additional time and labor, in the long run, you’ll appreciate the convenience of remotely operating the valve.
Waste Valve Leaks
Keep in mind it is not uncommon to have a leaking valve on occasion. This is often caused by debris that gets stuck in the valve when closing it after dumping. You can usually remove the obstruction and eliminate the leak by opening and closing the valve a few times during the next dump.
If you continually find liquid each time you remove the drain cap it’s time to replace the leaking waste valve.
Waste Valve Hard to Open and Close
Over time you may find the valve handle getting harder to pull open and/or push closed. If it gets too hard to open you may find the last pull of the handle will pull the rod right out of the valve blade and drastic measures will be needed to dump the tank. Of course you will have to replace the valve then anyway so why wait?
Often times a difficult to operate valve will also be a leaking valve. But you will need to determine if another valve isn’t the source of the leak or also is leaking.
Determining Which Valve Is Leaking
Before I go further, I need to say what will be obvious to most. You need to have access to a sewer connection to perform a waste valve replacement. You will have to dump then thoroughly flush each waste tank. After the tanks are flushed as clean as possible the tanks should be completely drained. All of this takes a lot of time. Out of courtesy to your fellow RVers this work should not be attempted at a public dump station.
Also, while most RVs have two holding tanks, one gray and one black, it is not unusual for RVs to have three tanks and it’s possible to have more.
So, now that you have all the tanks dumped, flushed, and drained you can determine which tanks are leaking by closing the valve of each tank individually… one at a time… and filling the tank with a few gallons of water. Depending on how much the tank leaks, you may have to wait several minutes to see a flow. Test each tank in this manor since you may have more that one valve leaking.
As an alternative to this testing, you may just want to replace all the valves. They are not expensive and a little preventive maintenance now could save you repeating the dump, flush and drain procedure in the future.
Removing the Old Waste Valve
RV builders are some of the most ‘creative’ folks you’ll ever meet. They can devise amazing ways to plumb waste holding tanks to the waste drain. Unfortunately this creativity sometimes overlooks the fact that, someday, the waste valves may need to be replaced.
Dave Allred, owner of All Rite RV and my RV tech, has told me a few horror stories of just trying to get access to a valve and needing to remove the holding tank to replace a another valve.
The usual problem stems from the need to spread the valve flanges wide enough… about 2 inches… to remove and replace the gate valve. Two inches may not seem like much but depending on how the manufacturer plumbed the waste system there just might not be enough give in the plumbing to do it.
So, before you make the decision to DIY it, be sure you know what you’re getting in to.
If you go ahead, you may want to consider making some modifications, if possible, to the plumbing to make future valve replacements easier.
For example, strategically cutting a pipe may make it much easier to replace the valve now and in the future. The pipe can be easily ‘repaired’ using a flexible coupling as shown here. These coupling slide over the joint and are sealed by tightening the hose clamps. Just make sure you think it through or get advice BEFORE you make the cut.
The rubber couplers are tough but you may need to install an additional hanger or bracket to support the weight of the plumbing.
I used flexible couplers on my RV plumbing modification several years ago and they are still doing fine. Click Here to see what I did.
Fortunately, on most RVs, removing and replacing a waste valve is straight forward and reasonably quick.
Once you have the old gate valve and flange seals removed, clean and dry the flanges.
Installing a New Waste Valve
Modern RVs use industry-standard parts and you should be able to find replacement gate valves at any RV store or repair shop.
If you have made modifications to the waste tank drain plumbing that require additional materials you may be able to get it all at your RV shop. Check there first as some parts are RV specific. Common plumbing supplies such as additional pipe, elbows and couplers not available at the RV shop can be purchased at any home improvement store.
The photo below shows a typical waste valve replacement kit. It contains a new gate valve, two new seals and new bolts and nuts.
For the purpose of good photography and so that you don’t have to look a some nasty old plumbing I’ve use new parts to illustrate my text. It should be easy enough for you to extrapolate what you see here to what your plumbing looks like.
Installing New Flange Seals
With the flanges clean and dry it’s time to install the flange seals.
Start by applying a liberal coat of petroleum jelly to each seal and the slide track for the gate. You don’t have to gob it on. The petroleum jelly acts as additional seal and helps the valve assembly seat properly on the seal. Once the new gate valve is installed, the petroleum jelly lubricates the gate and helps to keep it sliding easily.
Installing the Gate Valve Assembly
With the new seals placed on each flange it’s time to install the gate valve.
To insure you don’t dislodge the seals it is important that you spread the flanges far enough apart to easily slip the gate valve in to place. It’s not difficult or complicated and you should be able to feel and see that the valve is properly placed.
With the gate valve held in place by the two flanges, check for even spacing between the valve body and the flanges. Even spacing is a good indication the valve is placed properly.
Align the valve body so the bolt holes line up and install the bolts and nuts. With the nuts finger tight, again check for even spacing between the flange and valve body. Now operate the slide gate a couple of times. It should slide easily with no hesitation. If it doesn’t, disassemble the valve and reinstall the seals.
If the gate valve slides freely then tight the nuts to close the gap between the flanges and the valve body. The nuts should be snugged tight but not over tightened.
With the bolts tightened and the gap closed, check the valve operation again. It should slide easily with no hesitation. If it doesn’t, disassemble the valve and reinstall the seals.
If you are happy with the valve operation, you are done.
Congratulations you just saved yourself a lot of money by doing the job yourself!
Empty holding tanks with the press of a switch!
Eliminates bending, reaching and straining to open the waste valve on your RV. Attach the hose and press the switch to drain your tank. An LED indicator shows when valve is open, to avoid accidental leaks and spills.
Easily attaches to your manual valve. Draws less than 2.5 amps of 12-volt power during operation. Opens and closes in about 2 seconds. Manual override if power fails. Fully sealed motor. Made of aluminum, stainless steel and ABS plastic, so it will not rust or corrode. Includes switch with LED indicator and label for mounting near valve. Barker 3″ Auto Drain RV Waste Valve