Whether you're new to caravanning or have been travelling around New Zealand for years, understanding your caravan's water system can make life on the road much easier.
Your water system supplies the water you use for drinking, cooking, washing and showering, while also collecting the wastewater you produce. Keeping the system clean and working correctly is important for hygiene, convenience and trouble-free travelling.
In this guide, we'll explain how caravan and motorhome water systems work, the difference between fresh water and grey water, how to maintain your tanks and some of the common problems RV owners encounter.
How Does a Caravan Water System Work?
Although systems differ between caravans and motorhomes, most have several key components working together:
• Fresh water tank
• Water pump
• Water hoses and pipework
• Taps and shower
• Hot water system
• Grey water tank
• Waste pipes and fittings
• Tank level sensors
Fresh water is stored in a dedicated tank. When you turn on a tap, the water pump moves water from the tank through the pipework to your tap, shower or other outlet.
Once you've used that water, it flows into your wastewater or grey water system for storage until it can be disposed of appropriately.
Some RVs can also connect directly to an external water supply, depending on how the system has been designed.
What Is a Caravan Fresh Water Tank?
The fresh water tank stores clean water for use inside your caravan or motorhome.
Depending on your setup, you might use this water for:
• Drinking
• Cooking
• Washing dishes
• Showering
• Brushing your teeth
• General cleaning
Fresh water tanks vary considerably in capacity. The right size depends on the number of people travelling, how long you plan to stay away from water supplies and how much water you typically use.
Travellers who regularly stay off-grid will generally need greater water storage capacity than those who mainly use powered holiday parks with readily available facilities.
What Is Grey Water?
Grey water is wastewater from sinks, showers and similar household activities.
It shouldn't be confused with toilet waste, often referred to as black water.
For example, the water that disappears down your kitchen sink after washing the dishes becomes grey water. So does the water from your shower.
In a suitable caravan or motorhome setup, this wastewater is collected in a grey water tank until it can be disposed of at an appropriate location.
What Is Black Water?
Black water generally refers to wastewater containing human waste from a toilet.
Depending on your RV, toilet waste may be stored in a removable cassette or another dedicated waste system.
Black water requires careful handling and should only be emptied at an appropriate dump station or disposal facility.
Keeping fresh water, grey water and toilet waste systems properly separated is an important part of maintaining a hygienic RV.
How Often Should You Clean a Caravan Fresh Water Tank?
There's no single cleaning interval that's right for every caravan.
How often you need to clean your tank will depend on how frequently you use the RV, where you fill it, how long water remains in the tank and how the caravan is stored.
It's a good idea to clean and flush the system periodically and particularly when:
• Your caravan has been stored for an extended period
• The water develops an unusual taste or smell
• You aren't sure when the system was last cleaned
• Contamination may have occurred
• You're preparing the caravan after a long period without use
Regular maintenance can help prevent unpleasant tastes, smells and unwanted build-up within the system.
How Do You Clean a Caravan Water Tank?
Start by draining old water from the tank.
The tank and water lines can then be flushed and cleaned using a suitable product intended for caravan or motorhome fresh water systems.
Follow the directions supplied with the particular cleaning or sanitising product you're using, including the correct concentration and contact time.
Once complete, thoroughly flush the system with fresh water before refilling the tank.
Don't assume that household cleaning chemicals are suitable for an RV drinking-water system. Use a product designed for the application and follow its instructions.
Can You Drink Water From a Caravan Water Tank?
Potentially, yes, provided the entire system is designed for potable water and has been appropriately maintained.
The quality of the water coming out of the tap depends on more than just the tank.
Consider the cleanliness and suitability of the:
• Water source
• Filling hose
• Tank
• Pump
• Pipes
• Connectors
• Taps
If you're uncertain about the quality of the water source or condition of your system, don't assume the water is safe to drink.
Many travellers also carry separate drinking water as an additional precaution.
Why Does My Caravan Water Smell?
Unpleasant-smelling water can have several possible causes.
Water that's been sitting in a tank for a long period can become stale. Bacteria or other material may also accumulate within tanks, hoses and pipework if the system isn't regularly maintained.
If your fresh water develops an unusual smell or taste, drain the system and inspect and clean it before using the water for drinking.
If the smell is coming from a drain rather than your fresh water, the problem could instead be within the grey water system.
Food particles, soap, grease and other organic matter can accumulate and produce unpleasant odours.
How Do I Stop My Caravan Grey Water Tank From Smelling?
Regularly emptying and maintaining your grey water system is one of the best ways to control odours.
Try not to allow food scraps, fats and oils to enter your kitchen drain. These can accumulate inside pipework and tanks.
A suitable RV waste treatment product can also help maintain the waste system and control unpleasant smells.
If odours continue despite cleaning, check hoses, drains, seals and tank ventilation for possible problems.
Should I Empty My Water Tanks Before Storing My Caravan?
For longer periods of storage, it's generally sensible to avoid leaving stagnant water sitting in your fresh water system.
Drain the fresh water system as appropriate for your particular RV and clean it before putting the vehicle away for an extended period.
Grey water and toilet waste should also be emptied appropriately before storage.
Leaving a clean system makes getting your caravan ready for the next trip considerably easier.
Why Isn't Water Coming From My Caravan Taps?
If your tap isn't producing water, there are several things you can check.
Start with the obvious: is there actually water in the fresh water tank?
Next, check whether the water pump has power and is operating. Depending on the system, other potential causes include:
• Blown fuse
• Flat or low battery
• Blocked filter
• Air trapped in the system
• Kinked hose
• Faulty water pump
• Faulty tap microswitch
• Plumbing leak
If the pump continuously runs without delivering water, switch it off and investigate rather than allowing it to operate indefinitely.
Why Does My Caravan Water Pump Keep Running?
A pump that continues running after the taps have been turned off can indicate that the system isn't reaching the pressure required to switch the pump off.
Possible causes include a leak, air entering the system, low water level or an issue with the pump itself.
Check your tank level and look for obvious leaks around hoses, fittings and connections.
If you can't identify the problem, having the system inspected can prevent a small fault turning into water damage.
How Can I Tell How Much Water Is Left in My Tank?
Many modern caravans and motorhomes use tank level sensors connected to a control panel or monitoring system.
These allow you to check approximately how much fresh or waste water is in a tank without physically inspecting it.
Tank sensors are particularly useful when freedom camping because knowing your remaining fresh water and available grey water capacity can help determine how long you can comfortably remain off-grid.
What Size Fresh Water Tank Do I Need?
There's no perfect tank size for everyone.
Think about:
Number of travellers: More people means greater water consumption.
Length of your trips: Longer off-grid stays require more capacity.
Showering: On-board showers can dramatically increase water consumption.
Available payload: Water is heavy. One litre of water weighs approximately one kilogram, so carrying an additional 100 litres means roughly 100kg of additional weight.
Access to water: If you frequently stay at campgrounds, you may not need to carry as much water as someone who spends days off-grid.
Rather than simply installing the largest tank possible, balance capacity against your vehicle's available space and legal payload.
Fresh Water vs Grey Water: What's the Difference?
The simplest way to remember it is:
Fresh water is the clean water you're carrying to use.
Grey water is water you've already used in sinks, showers and similar applications.
Black water contains toilet waste.
Each requires its own appropriate storage, maintenance and disposal process.
Caravan Water System Tips
A few simple habits can help keep your water system in good condition:
• Use a dedicated drinking-water-safe filling hose where appropriate
• Keep hose ends clean and capped when stored
• Regularly inspect hoses and fittings for leaks
• Check your water pump and filters
• Clean your fresh water tank periodically
• Don't leave grey water sitting unnecessarily
• Keep food and grease out of drains
• Inspect tank sensors if readings become unreliable
• Drain and prepare the system appropriately before long-term storage
Small leaks are also worth addressing quickly. A minor plumbing leak inside a caravan can cause significant damage if it goes unnoticed.
Caravan Water & Plumbing Supplies at RV Mega
Whether you're maintaining an existing water system or upgrading your caravan or motorhome, having the correct components makes the job easier.
At RV Mega, we stock a wide range of caravan and motorhome water and plumbing products, including pumps, hoses, tanks, fittings, connectors, sensors and waste treatment products.
Our team can also help you identify suitable products for your particular caravan or motorhome.
Understanding your water system and giving it regular attention can help you enjoy cleaner water, fewer unpleasant odours and fewer plumbing surprises while travelling around New Zealand.
Frequently Asked Questions
How long can water stay in a caravan water tank?
There isn't a universal safe period because water quality depends on factors including the original water source, temperature, cleanliness of the tank and whether contamination has occurred. If water has been sitting unused for an extended period, it's sensible to drain, clean and refill the system before drinking from it.
How do I get rid of a bad smell from my caravan water tank?
Drain the tank and clean and flush the fresh water system using a suitable product according to its instructions. If the smell persists after cleaning, the tank, hoses and pipework may require further inspection.
Whether you're new to caravanning or have been travelling around New Zealand for years, understanding your caravan's water system can make life on the road much easier.
Your water system supplies the water you use for drinking, cooking, washing and showering, while also collecting the wastewater you produce. Keeping the system clean and working correctly is important for hygiene, convenience and trouble-free travelling.
In this guide, we'll explain how caravan and motorhome water systems work, the difference between fresh water and grey water, how to maintain your tanks and some of the common problems RV owners encounter.
How Does a Caravan Water System Work?
Although systems differ between caravans and motorhomes, most have several key components working together:
• Fresh water tank
• Water pump
• Water hoses and pipework
• Taps and shower
• Hot water system
• Grey water tank
• Waste pipes and fittings
• Tank level sensors
Fresh water is stored in a dedicated tank. When you turn on a tap, the water pump moves water from the tank through the pipework to your tap, shower or other outlet.
Once you've used that water, it flows into your wastewater or grey water system for storage until it can be disposed of appropriately.
Some RVs can also connect directly to an external water supply, depending on how the system has been designed.
What Is a Caravan Fresh Water Tank?
The fresh water tank stores clean water for use inside your caravan or motorhome.
Depending on your setup, you might use this water for:
• Drinking
• Cooking
• Washing dishes
• Showering
• Brushing your teeth
• General cleaning
Fresh water tanks vary considerably in capacity. The right size depends on the number of people travelling, how long you plan to stay away from water supplies and how much water you typically use.
Travellers who regularly stay off-grid will generally need greater water storage capacity than those who mainly use powered holiday parks with readily available facilities.
What Is Grey Water?
Grey water is wastewater from sinks, showers and similar household activities.
It shouldn't be confused with toilet waste, often referred to as black water.
For example, the water that disappears down your kitchen sink after washing the dishes becomes grey water. So does the water from your shower.
In a suitable caravan or motorhome setup, this wastewater is collected in a grey water tank until it can be disposed of at an appropriate location.
What Is Black Water?
Black water generally refers to wastewater containing human waste from a toilet.
Depending on your RV, toilet waste may be stored in a removable cassette or another dedicated waste system.
Black water requires careful handling and should only be emptied at an appropriate dump station or disposal facility.
Keeping fresh water, grey water and toilet waste systems properly separated is an important part of maintaining a hygienic RV.
How Often Should You Clean a Caravan Fresh Water Tank?
There's no single cleaning interval that's right for every caravan.
How often you need to clean your tank will depend on how frequently you use the RV, where you fill it, how long water remains in the tank and how the caravan is stored.
It's a good idea to clean and flush the system periodically and particularly when:
• Your caravan has been stored for an extended period
• The water develops an unusual taste or smell
• You aren't sure when the system was last cleaned
• Contamination may have occurred
• You're preparing the caravan after a long period without use
Regular maintenance can help prevent unpleasant tastes, smells and unwanted build-up within the system.
How Do You Clean a Caravan Water Tank?
Start by draining old water from the tank.
The tank and water lines can then be flushed and cleaned using a suitable product intended for caravan or motorhome fresh water systems.
Follow the directions supplied with the particular cleaning or sanitising product you're using, including the correct concentration and contact time.
Once complete, thoroughly flush the system with fresh water before refilling the tank.
Don't assume that household cleaning chemicals are suitable for an RV drinking-water system. Use a product designed for the application and follow its instructions.
Can You Drink Water From a Caravan Water Tank?
Potentially, yes, provided the entire system is designed for potable water and has been appropriately maintained.
The quality of the water coming out of the tap depends on more than just the tank.
Consider the cleanliness and suitability of the:
• Water source
• Filling hose
• Tank
• Pump
• Pipes
• Connectors
• Taps
If you're uncertain about the quality of the water source or condition of your system, don't assume the water is safe to drink.
Many travellers also carry separate drinking water as an additional precaution.
Why Does My Caravan Water Smell?
Unpleasant-smelling water can have several possible causes.
Water that's been sitting in a tank for a long period can become stale. Bacteria or other material may also accumulate within tanks, hoses and pipework if the system isn't regularly maintained.
If your fresh water develops an unusual smell or taste, drain the system and inspect and clean it before using the water for drinking.
If the smell is coming from a drain rather than your fresh water, the problem could instead be within the grey water system.
Food particles, soap, grease and other organic matter can accumulate and produce unpleasant odours.
How Do I Stop My Caravan Grey Water Tank From Smelling?
Regularly emptying and maintaining your grey water system is one of the best ways to control odours.
Try not to allow food scraps, fats and oils to enter your kitchen drain. These can accumulate inside pipework and tanks.
A suitable RV waste treatment product can also help maintain the waste system and control unpleasant smells.
If odours continue despite cleaning, check hoses, drains, seals and tank ventilation for possible problems.
Should I Empty My Water Tanks Before Storing My Caravan?
For longer periods of storage, it's generally sensible to avoid leaving stagnant water sitting in your fresh water system.
Drain the fresh water system as appropriate for your particular RV and clean it before putting the vehicle away for an extended period.
Grey water and toilet waste should also be emptied appropriately before storage.
Leaving a clean system makes getting your caravan ready for the next trip considerably easier.
Why Isn't Water Coming From My Caravan Taps?
If your tap isn't producing water, there are several things you can check.
Start with the obvious: is there actually water in the fresh water tank?
Next, check whether the water pump has power and is operating. Depending on the system, other potential causes include:
• Blown fuse
• Flat or low battery
• Blocked filter
• Air trapped in the system
• Kinked hose
• Faulty water pump
• Faulty tap microswitch
• Plumbing leak
If the pump continuously runs without delivering water, switch it off and investigate rather than allowing it to operate indefinitely.
Why Does My Caravan Water Pump Keep Running?
A pump that continues running after the taps have been turned off can indicate that the system isn't reaching the pressure required to switch the pump off.
Possible causes include a leak, air entering the system, low water level or an issue with the pump itself.
Check your tank level and look for obvious leaks around hoses, fittings and connections.
If you can't identify the problem, having the system inspected can prevent a small fault turning into water damage.
How Can I Tell How Much Water Is Left in My Tank?
Many modern caravans and motorhomes use tank level sensors connected to a control panel or monitoring system.
These allow you to check approximately how much fresh or waste water is in a tank without physically inspecting it.
Tank sensors are particularly useful when freedom camping because knowing your remaining fresh water and available grey water capacity can help determine how long you can comfortably remain off-grid.
What Size Fresh Water Tank Do I Need?
There's no perfect tank size for everyone.
Think about:
Number of travellers: More people means greater water consumption.
Length of your trips: Longer off-grid stays require more capacity.
Showering: On-board showers can dramatically increase water consumption.
Available payload: Water is heavy. One litre of water weighs approximately one kilogram, so carrying an additional 100 litres means roughly 100kg of additional weight.
Access to water: If you frequently stay at campgrounds, you may not need to carry as much water as someone who spends days off-grid.
Rather than simply installing the largest tank possible, balance capacity against your vehicle's available space and legal payload.
Fresh Water vs Grey Water: What's the Difference?
The simplest way to remember it is:
Fresh water is the clean water you're carrying to use.
Grey water is water you've already used in sinks, showers and similar applications.
Black water contains toilet waste.
Each requires its own appropriate storage, maintenance and disposal process.
Caravan Water System Tips
A few simple habits can help keep your water system in good condition:
• Use a dedicated drinking-water-safe filling hose where appropriate
• Keep hose ends clean and capped when stored
• Regularly inspect hoses and fittings for leaks
• Check your water pump and filters
• Clean your fresh water tank periodically
• Don't leave grey water sitting unnecessarily
• Keep food and grease out of drains
• Inspect tank sensors if readings become unreliable
• Drain and prepare the system appropriately before long-term storage
Small leaks are also worth addressing quickly. A minor plumbing leak inside a caravan can cause significant damage if it goes unnoticed.
Caravan Water & Plumbing Supplies at RV Mega
Whether you're maintaining an existing water system or upgrading your caravan or motorhome, having the correct components makes the job easier.
At RV Mega, we stock a wide range of caravan and motorhome water and plumbing products, including pumps, hoses, tanks, fittings, connectors, sensors and waste treatment products.
Our team can also help you identify suitable products for your particular caravan or motorhome.
Understanding your water system and giving it regular attention can help you enjoy cleaner water, fewer unpleasant odours and fewer plumbing surprises while travelling around New Zealand.
Frequently Asked Questions
How long can water stay in a caravan water tank?
There isn't a universal safe period because water quality depends on factors including the original water source, temperature, cleanliness of the tank and whether contamination has occurred. If water has been sitting unused for an extended period, it's sensible to drain, clean and refill the system before drinking from it.
How do I get rid of a bad smell from my caravan water tank?
Drain the tank and clean and flush the fresh water system using a suitable product according to its instructions. If the smell persists after cleaning, the tank, hoses and pipework may require further inspection.
Why does my caravan water pump pulse?
A pump may cycle or pulse because of pressure changes in the water system. Excessive or unusual cycling can indicate issues such as a leak, air in the system or pump/pressure settings that need attention.
Can I put bleach in my caravan water tank?
Don't add household chemicals to a drinking-water system without confirming they're appropriate for your particular system and following an approved sanitisation procedure. A dedicated potable-water tank cleaning or sanitising product is generally the simpler option.
How do you empty a caravan grey water tank?
Use the RV's designated wastewater outlet and hose and dispose of the contents at an appropriate wastewater or dump facility. Follow the requirements applicable to the location where you're staying.
Does grey water include toilet waste?
No. Grey water generally comes from sinks and showers. Toilet waste is treated separately and is commonly referred to as black water.
Should I leave my caravan water tank full or empty when stored?
For extended storage, it's generally preferable to drain the system according to the manufacturer's recommendations rather than leave water sitting stagnant for a long period.
How much does a full caravan water tank weigh?
Water weighs approximately 1kg per litre. That means 50 litres adds around 50kg, while 100 litres adds around 100kg to your caravan or motorhome.
A pump may cycle or pulse because of pressure changes in the water system. Excessive or unusual cycling can indicate issues such as a leak, air in the system or pump/pressure settings that need attention.
Can I put bleach in my caravan water tank?
Don't add household chemicals to a drinking-water system without confirming they're appropriate for your particular system and following an approved sanitisation procedure. A dedicated potable-water tank cleaning or sanitising product is generally the simpler option.
How do you empty a caravan grey water tank?
Use the RV's designated wastewater outlet and hose and dispose of the contents at an appropriate wastewater or dump facility. Follow the requirements applicable to the location where you're staying.
Does grey water include toilet waste?
No. Grey water generally comes from sinks and showers. Toilet waste is treated separately and is commonly referred to as black water.
Should I leave my caravan water tank full or empty when stored?
For extended storage, it's generally preferable to drain the system according to the manufacturer's recommendations rather than leave water sitting stagnant for a long period.
How much does a full caravan water tank weigh?
Water weighs approximately 1kg per litre. That means 50 litres adds around 50kg, while 100 litres adds around 100kg to your caravan or motorhome.