Extra-Large Grey Water Tanks: Which Campers Have Them?

RVs typically have three tanks: one for fresh water, one for grey water, and one for black water. Grey water tanks capture wastewater from sinks and showers, while black water tanks are for toilet wastewater. Grey water tanks are relatively easy to maintain and don't require the same powerful chemicals as black water tanks. They can be cleaned with a mixture of vinegar and baking soda, or dish soap and warm water. RVs are now being built with a combination black and grey water tank, but this isn't common as it requires a very large tank.

If you're looking for an extra-large grey water tank for your camper, you can purchase RV grey water holding tanks with capacities ranging from 5 to 202 gallons. These tanks are made from durable materials like rotationally-molded polyethylene resin and can be bought as blank tanks or with pre-installed fittings.

How often should you empty your grey water tank?

There is no hard and fast rule about when to empty your grey water tank. It depends on how much you use it and how many people are using it. If you are travelling with a large number of people, you may need to empty your tank every other day. If it's just you and your partner, once a week may be enough.

A general rule of thumb is to wait until your tank is about two-thirds full before emptying it. This creates a much better "flow" when dumping, making the process much more efficient.

Some recreational vehicles come with systems to show you exactly how full your tanks are. However, these sensors don't always work well and can give incorrect readings. So it's important to stay aware of how much waste you are accumulating.

Your grey water tank will gradually fill up over time as you go about your daily activities: washing your hands, cleaning up after dinner, or taking an onboard shower. Each time you do any of these things, your grey water tank will collect the waste and begin to fill up.

If you are travelling alone and tend to shower at campground facilities instead of in your unit, you might be able to go a week or more without draining your grey water tank. On the other hand, if you are travelling with a family and everyone showers onboard every day, you will need to drain your grey water tank more regularly.

Most RVs will have a tank-holding sensor to alert you when your tanks are filling up. However, on some smaller travel trailers, you might not know until your drains stop draining or water starts bubbling up into the bathtub or shower.

How to Empty Your Grey Water Tank

To empty your grey water tank, follow these steps:

• Be sure you're dumping in a designated city sewer connection. Although grey water may be less toxic than black water (and is even legal to dump on the ground in some states), it's best practice to dump your tanks into the actual sewer, where the water can be treated and reused.
• Always empty the black water tank first.
• Wear rubber gloves to protect your hands.
• Remove the cap that covers the holding tank outlets and connect your sewer hose.
• Put your sewer hose in the dump hole, at least four or five inches deep.
• Secure it in place. You can use a brick or the cover of the dumping station to secure the hose firmly.
• Open the black water valve and let the tank drain. Close the valve when you can no longer hear any liquid coming through the hose.
• Open the grey water tank valve.
• Flush your tanks by refilling them and draining them again.
• Close your valves and disconnect the hose from the outlet.
• Lift the sewer hose from the end of the RV to the dump hole to get rid of any remaining water in the hose.
• Run water through it to rinse it thoroughly.
• Disconnect the hose from the hole and rinse the area around it in case of any spillage.
• Cover the hole and store your sewer hose.
• Add RV water tank treatment to your tanks.

How do you clean your grey water tank?

To clean your grey water tank, you'll first want to prevent "stuff" from getting into the tank. Use a kitchen sink strainer and a hair strainer in the shower to catch food particles and hair. Scrape and wipe off dishes well before washing, and if using an RV dishwasher, be aware that it is not connected to a garbage disposal, so food particles need to be scraped off and wiped away.

When it's time to clean the tank, do not use bleach. Bleach is hard on rubber and can damage valves and seals. Instead, use a cleaning agent such as Dawn dish detergent, Calgon water softener, dishwasher gel, or laundry detergent.

Fill the tank with water and, if possible, drive your RV around to let the cleaner slosh around and break down the gunk. Let the cleaner stay in the tank for a day or two, then rinse the tank. If the tank doesn't seem clean enough, repeat the process. You can also use vinegar and baking soda to clean the tank, but be ready for a strong smell.

To prevent clogs, use a gentle cleaning treatment rather than trying to snake the line. Some campers have reported success using a mild dish detergent, like Dawn, along with hot water, to help break down greasy buildup.

What is the difference between grey water and black water?

Recreational vehicles typically have three tanks: one for fresh water, and two for wastewater. The two wastewater tanks are for grey water and black water. Grey water tanks capture liquids from sinks and showers, while black water tanks hold wastewater from the toilet. Grey water tanks can also capture water from the kitchen sink, shower, and dishwasher. Black water tanks, on the other hand, contain water from the toilet, as well as wastewater from bathrooms, kitchens, and dishwashers, which may contain faecal matter, urine, and grease.

Grey water has not come into contact with solid human waste, and therefore has a lower level of contamination than black water. Grey water may contain soap particles, fat, oil from cooking, hair, and flakes of human skin. Black water, on the other hand, comes into contact with faecal matter, which can harbour harmful bacteria and disease-causing pathogens. This waste does not break down quickly or effectively enough for domestic irrigation without risking contamination. Grey water, due to its lower level of contamination, can be broken down and reabsorbed more quickly and safely.

Grey water tanks are available in capacities ranging from 5 gallons to 200 gallons, and can be purchased with pre-installed fittings or as blank tanks with DIY custom fittings. Grey water can be reused in irrigation and constructed wetlands, as well as for flushing toilets and washing, as long as no harmful chemicals are present. It can also be used in gardens with little to no treatment, although it is recommended to minimise the use of harsh chemicals and use natural cleaning products, low or no-sodium laundry detergents, and soaps.

Black water, due to its higher level of contamination, requires biological or chemical treatment and disinfection for treatment. The most common treatment system is the aerated system, which involves settling wastewater solids, aerating the effluent to assist in the bacterial breakdown of organic matter, and disinfection, usually by chlorine pellets.

How do you know when your grey water tank is full?

There are several ways to tell when your grey water tank is full. One way is to wait until it overflows, but it's better to keep an eye on your tank levels and understand your water usage habits. Many first-time RV users learn about their grey water tank when they notice a funny smell and find standing water backed up in the shower.

Sensors

Most RVs have sensors that will give you an approximate tank level. However, these sensors can be unreliable. Over time, they can get dirty and fail to give an accurate reading. Residue can stick to the sides of the tank, preventing sensors from correctly measuring how much wastewater is in the holding tank. Even new sensors may give an incorrect reading because of paper or other waste sticking to the sensor.

Drains

If your grey water tank is full, the water will stop draining from your sinks and showers. The water may even back up into your sinks and showers. If this happens, you will need to empty the tank.

Weight

When the grey water tank is full, it will add extra weight to your RV, which can make it harder to drive.

Experience

After a while, you will get a sense of how long it takes for your grey water tank to fill up.

Maintenance

To avoid overflow, it's recommended that you empty your grey water tank when it is about two-thirds full. This will help prevent clogging and unpleasant odours.

How do you dump waste from your grey water tank?

To empty your grey water tank, you'll need to follow a few simple steps. Firstly, make sure you're dumping your waste in a designated city sewer connection. Although grey water is less toxic than black water, it's best to dispose of it in the sewer, where it can be treated and reused. Always wear gloves to protect your hands and avoid any splashes.

Start by removing the cap that covers the holding tank outlets and connect your sewer hose. Put your hose into the dump hole, securing it in place with a brick or the cover of the dumping station. Open the black water valve first and let the tank drain completely. Close the valve when you can no longer hear liquid coming through the hose.

Next, open the grey water tank valve. Flush your tanks by refilling them and draining them again. Close the valves, disconnect the hose from the outlet, and lift the hose from the RV to the dump hole to remove any remaining water. Rinse the hose thoroughly with water, then disconnect it from the hole and rinse the area. Now your sewer hose is ready to be stored away.

Frequently asked questions