Water in a campervan involves three separate systems: fresh water for the taps and shower, grey water from the sink, washbasin and shower, and the toilet cassette. Do not mix them up. Fill fresh water at a point confirmed for that purpose, empty grey water into a service drain, and empty the toilet cassette at a separate waste-disposal point.
On your first trip, you do not need to memorise the entire installation. Before setting off, it is enough to know where the fresh-water filler, level panel, grey-water valve and toilet-cassette hatch are. Your vehicle manual and the rules at the service point will guide you through the rest.
Contents
The three systems to tell apart
Most confusion comes from treating all water in a campervan as if it were in one tank. In practice, these are three separate systems, serviced in different places.
| What is it? | Where does it come from? | What do you do with it? |
|---|---|---|
| Fresh water | From the onboard tank, filled through an external filler point. | Use it at the tap, in the shower and sometimes to flush the toilet. |
| Grey water | Produced when washing dishes and hands, or using the shower. | Empty it through a valve into a service drain at a camper service point or campsite. |
| Toilet cassette | A removable toilet waste tank, separate from grey water. | Empty it only at a disposal point intended for toilet waste. |
In some campervans, the toilet flush uses fresh water. In others, it has a separate small tank. One rule remains the same: the contents of the toilet cassette do not go into the grey-water tank. If you are unsure how the toilet works in your vehicle, ask for a demonstration when you collect it. Elnagh notes that toilet layouts and component locations can vary between models.
What to check before using the water system for the first time
Do this short walk-round while you are still at the campsite or rental depot, where someone can answer questions. Looking for a valve after dark with a full grey-water tank is not a good time to learn the system.
- Find the external fresh-water filler and check how it is marked.
- Check whether the control panel shows the fresh-water and grey-water levels.
- Ask where the grey-water valve is and how it opens and closes.
- Open the toilet-cassette hatch and see how to remove the cassette safely.
- Find out whether the water pump is switched on at the panel or starts when you open a tap.
Do not assume that the valve will always be in the same place. The Elnagh manual shows that a grey-water valve may be beneath the floor or in the garage, depending on the vehicle design. This is why the manual for your own campervan matters more than a video about a different model.
If you are collecting a campervan for the first time, also use our first campervan trip checklist. It covers the handover, the first stop and the details worth confirming before your journey.
How to fill the fresh-water tank
Look for a point marked drinking water, fresh water or a water supply point for campervans. At a campsite, the simplest approach is to ask reception which tap you may use to fill the tank. At a public location, do not assume that every outdoor tap supplies water suitable for the vehicle system.
Before filling, check three things: that you have a clean hose used only for fresh water, that its end is not lying on the ground, and that you know the tank capacity and current level. Store the water hose separately from gloves, toilet chemicals and waste-disposal equipment.
The process is usually straightforward:
- Open the filler marked for fresh water.
- Insert the clean hose and turn on the tap slowly to check that the connection is secure.
- Watch the level on the panel, or fill to the point stated in the vehicle manual.
- Turn off the tap, remove the hose and close the filler.
Do not copy one procedure to every campervan. The manufacturer may specify a different filler position, vent, overflow or drain valve.
Water that has stood in the tank and pipework for a long time should not be treated as fresh. The Polimer manual recommends filling only with fresh water and flushing the tank and pipes before use after storage. In practice, after collecting a campervan, after winter or after a long break, ask the owner whether the system has been drained and flushed.
Can you drink water from the tank?
Do not automatically assume that water from a campervan tank is safe to drink. It should come from a tap marked as drinking water, and you should know that the system was recently flushed and that the water has not stood in it for a long period. If you do not know the vehicle's history, for example with a rental campervan or after winter storage, use tank water for washing and keep separate drinking and cooking water until the owner confirms the condition of the system.
This cautious approach matters especially after a long stop. Simply adding fresh water is not enough: flush the tank and pipework in line with the manufacturer's instructions.
Do not run the pump with an empty tank. The same manual warns that operating a pump without water can cause overheating and damage. If no water comes from the tap, first check the water level, the panel settings and the vehicle handover instructions instead of leaving the tap open.
Where and how to empty grey water
Grey water is used water from the sink, washbasin and shower. It does not contain toilet-cassette waste, but it still contains soap, detergents, food residues and deposits. It therefore needs its own designated drain.
Look for signs such as Camper Service, grey water, waste water or service point, or a wastewater-disposal symbol. A suitable station has a drain you can position the campervan over and clearly separates grey-water disposal from the toilet-cassette point and the fresh-water supply.
Position the campervan so the drain is beneath the correct part of the vehicle. Apply the parking brake, check that nobody is near the valve, open it as instructed for your campervan and wait for the tank to empty. Before driving away, close the valve and look beneath the vehicle. This quick habit helps you notice an unclosed valve immediately rather than several kilometres later.
The Elnagh manual states that grey water should be emptied only at camper service points or campsite drains. A street drain, grass verge, ditch or car park is not a replacement. If grey water smells or the drain runs slowly, read our guide to campervan drain smells, grey water and shower trays after emptying the tank.
The toilet cassette is a separate service task
A toilet cassette is not a bucket for grey water. It is a sealed waste tank that you remove from outside the vehicle and take to a designated disposal point. Thetford advises finding a dedicated disposal station, emptying the cassette into the appropriate drain using the air-release button, then rinsing it with clean water.
Before removing the cassette, make sure the toilet blade inside is closed. Only then open the external hatch. The order of steps, release mechanism and air-release button vary by toilet model, so try it for the first time during the handover, not at a busy service point.
Use only the product and dosage stated by the toilet manufacturer or on the product label. Do not pour chemicals into unlabelled bottles, mix products or use them in the grey-water tank. For everyday hygiene, paper and odours, see our guide to a portable toilet in a campervan.
What to do when there is no service point
The absence of a service point does not change what each tank is for. If you are running low on fresh water, buy water for essential needs or find a campsite, marina or camper service point whose operator confirms that you may fill up. If the grey-water tank or toilet cassette is filling up, plan a trip to a service point before using the system further.
Before you arrive, check four things on the venue's website or by phone: whether it accepts campervans without an overnight stay, whether it handles grey water and toilet cassettes separately, whether fresh water is available, and whether there is a charge or set opening hours. A map photo may show an old facility, so confirmation from the operator is more reliable than a pin alone.
Take a clean water hose, simple adapters that fit your hose, service gloves and a small torch. A jerry can can help carry fresh water from a confirmed source to the campervan, but it does not replace a place to empty grey water or a toilet cassette.
Editorial example: a weekend for two
Two people collect a campervan on Friday afternoon and head to a campsite for two nights. On arrival, they first ask reception where the fresh-water tap is and where the two service drains are. After filling the tank, they check the panel and briefly run a tap to confirm that the pump works.
On Saturday, after showering and washing dishes, they check the grey-water level instead of waiting for a full-tank warning. Before leaving on Sunday, they empty grey water over the service drain, empty the toilet cassette at its separate point and rinse it as instructed. Only then do they set off. This prevents the final morning becoming a search for a disposal point with full tanks.
This is not a fixed timetable. With shorter showers, campsite facilities and simple cooking, servicing may be needed later. What matters is monitoring the levels and planning where to use the facilities, not counting days against a universal chart.
System hygiene and the end of a trip
After a trip, do not leave several days' worth of grey water in the tank. Empty it at a service point, remove debris from the sink and shower-tray strainers, then dry and air the bathroom. An odour is not a normal feature of a campervan. It usually signals that you should check the drain, tank, cassette or moisture.
If the vehicle will be stored for a longer period or frost is expected, follow its manufacturer's manual exactly. Draining a system for storage is a different procedure from ordinary servicing after a weekend. Our guide to preparing a campervan for autumn and winter will help.
When packing for your first trip, also see our complete campervan packing checklist and outdoor kitchen accessories. A hose, gloves and a small torch may not look exciting, but they make a first service stop much easier.