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How to Dump RV Black and Grey Water Tanks: A Guide

Updated: Jun 3

Learn how to dump your RV black tanks easily when you're parked at a campground or boondocking out in the wild.

How to clean RV black tank

One of the biggest perks of living in an RV is that it comes with a plumbing system that mirrors the one in a traditional home. Having freshwater for drinking, cooking, washing dishes, and showering on the road is a blessing. But where does all that wastewater go? The black and grey water tanks of your RV make sure that all the wastewater from your RV stays in an enclosed space till it is time for you to empty them. Read on to find out how to do just that easily and hassle-free.

Black Water vs Grey Water RV Tank

It is important to learn about your RV's holding tanks before you hit the road. You won't just need to fill these tanks but also empty them while you're on your trip. Most RVs have three holding tanks; a freshwater tank that holds all the water you drink and/or use for cooking, a grey water tank that stores all the water that gets drained from the RV other than that from the toilet (dishwasher, shower), and a blackwater tank that holds all the water that gets drained from the toilet.

A lot of smaller motorhomes and older RV models don't have separate grey and blackwater tanks, they only have one black tank where all the waste water gets stored. The idea of having two separate tanks for waste water is to make sure that all wastewater from the RV bathroom remains separate from all other kinds of water in your RV and that you don't have to dump your tanks as often as you would if you had just the one tank.

Both black and grey water tanks need to be dumped appropriately once they are full so you can keep using the facilities in your RV without any 'stinky' incidents.

Black Water Tank Dumping Equipment

Here is all the equipment you will need to dump your RV black and grey water tanks.

Dumping RV Black and Grey Water Tanks: Step by Step Guide

Dumping RV tanks can seem like a daunting task, especially to new RVers. However, some quick tips can make the process go smoothly. Before you connect your tank to the dumping station make sure:

  • Your RV is parked as close to the dumping station so that your hose can easily reach the station without getting too taut

  • Most RV dumping stations will already be designed in a way that your RV is parked uphill to the station so that it is easier to dump. If not, use an angeled elbow to make sure the pipe is at a 45 or 90-degree angle to the station

  • Make sure to close the air vent in the RV bathroom before you start dumping otherwise, the not-too-pleasant odors will go in and stay

  • Put on your gloves before you begin attaching the hose, we also recommend adding a mask for good measure

RV black tank flush system

Here is a step-by-step guide on how to empty your RV blackwater tank:

Step 1: Figure Out the Position of the Gate Valves

The first thing you need to do is find the gate valves for the black and grey water tanks on your RV. The placement is different as per the type and model for your RV so refer to the RV manual for their location or just ask the RV dealer/owner you buy it from. The gate valves are usually right next to the freshwater valve on your RV. A lot of RVs have a larger blackwater gate valve than a greywater one but this is not always the case.

Both the blackwater and greywater gate valves will be located close to where the plumbing for both tanks come together and there will be a lid below the valves. This lid is where you will connect your sewer hose. Both valves will have a handle on top that you will rotate to open and close the valves. Both valves will be marked with their names so there is no confusion.

Attach the RV Sewer Hose

Once you've identified the two gate valves, make sure they are fully closed before you open the lid below the valves. Remove the lid and attach your sewer hose to the lid using the sewer fitting wrench to make sure it is nice and snug. If you want to attach a transluscent elbow or a sewer support to the hose, do that before you attach the pipe to the lid. Once the hose is secured to the lid attach the other end of the hose to the dumping station or septic hole.

Open the Valves and Empty the Black Tank

Make sure both ends of the sewer hose are fully secure and then open the blackwater tank gate valve first. Just rotate it so that it is fully open. You can use the transluscent elbow to check if the hose has started dumping waste. Keep the valve open until the tank is fully empty, again the clear elbow will help you see when the flow stops. Once the tank is empty close the blackwater tank gate valve completely.

Next, open the greywater tank gate valve and let that water run. By dumping the grey water tank after the black water one you will help clean the sewer hose as well. Let the greywater tank empty completely and then close that valve as well.

Clean the RV Black and Greywater Tank

You don't have to do this everytime you dump your tanks, but it is a good idea to clean your black and greywater tanks after you've emptied them. To do this you can use an elbow attachment with a sewer tank rinser that let's you attach a separate garden hose to the lid to fill the tanks with water. These elbow attachments come with a gate valve that can be locked to help fill both the black and greywater tanks with clean water. You can then open the gate valve to drain all the water again effectively cleaning the tanks. This process can be repeated until you see clear water come out of the tanks.

If you don't want to clean the tanks you can simply close both the black and grey water tank valves and remove the hose. Place the lid back on but keep the sewer hose attached to the dumping station or septic hole. Use a garden hose (not the freshwater one) to run clean water into the sewer hose from the side you just detached from the lid. Run the water till the hose is clean. Remove the sewer hose from the dumping station.

Pack Everything Up

Once you're done dumping your tanks make sure to pack all your clean equipment safely in a bag. Store in a cool, dry place. Make sure to wash your hands thoroughly after you're done.

Where Can You Dump Your RV Blackwater Tank?

You can't dump your blackwater tank just anywhere. Here are some places where you can:

RV blackwater tank cleaning service near me

RV Parks and Campgrounds

Both private and national RV parks and campgrounds have designated dumping stations where you can safely dispose off your black tank waste. Most parks with full hook-ups will have the charges to use the dumping station built into the parking fee, but for those that don't, you might have to pay extra to use the facilities.

RV Dump Stations/Sanitation Facilities

A lot of government-certified sanitation facilities and dumping stations also allow RVers to dump their black tanks for a small fee. Make sure to call ahead and check if a particular facility allows you to do so before going on your trip.

Truck Stops

Some truck stops also have dumping stations that RVers can use for a small fee. Again, make sure to check if a truck stop has that facility before planning your route.

Rest Areas and Welcome Centers

Some RV rest areas and welcome centers are equipped with septic holes that can be used to dump your RV tanks. You can find this info on their website.

Honey Wagon Services

Don't want to dump your RV tanks yourself? Honey Wagon Services can do it for you. Usually operated by waste management companies, honey wagon services would send sanitation trucks to your home or campsite and pump your tanks for you.

How Often Should you Empty Your RV Black Tank?

How often you should dump your black tank depends on the size of the tank and your usage. Most RVs have sensors that show you how full your freshwater, greywater, and blackwater tanks are in increments or percentages. But don't wait till your tanks are 100% full to dump them as this may cause some very unpleasant incidents. A good rule of thumb is to dump your black tanks when the sensor shows that the tanks are 3/4 or 75% full.

Can you Empty RV Black Tank at Home?

Legally, no, you can't empty your black tank at home. Although some states and municipal authorities do allow dumping RVs at home, most don't. However, there isn't much difference in dumping your RV tanks and the septic tank in your homes. Simply open the septic hole near your house and dump the holding tanks with a sewer hose like you would at a dumping station.

Dump Them Tanks

Dumping your RV holding tanks isn't that hard once you get the hang of it. If you're planning on boondocking make sure you park close to a dump station or carry a portable blackwater dumping tank with you on your adventure.


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