Fresh-water, dedicated drinking-water and grey-water tanks do different jobs. The exact arrangement varies between caravans, so identify every tank, hose, valve and pickup point before planning capacity or maintenance.
Fresh-water tanks
Fresh-water tanks usually supply sinks, showers and sometimes toilet flushing through a pump. Some caravans have one tank; others have two or more tanks that can be selected or isolated. Nominal capacity does not guarantee that every litre is usable.
Dedicated drinking-water tanks
A separate potable tank or container can protect drinking and cooking water from general-use demand. It may use a separate tap or pump. Confirm that the tank, hose and fittings are suitable for drinking water and are not used for other liquids.
Grey-water tanks
Grey water is wastewater from sinks and showers, not toilet waste. A grey-water tank allows the caravan to retain this water until it can be disposed of appropriately. Capacity can limit how long a caravan remains self-contained even when fresh water is still available.
Grey-water rules vary by state, council, campground and land manager. Follow site instructions and use approved wastewater facilities where required; do not assume discharge onto the ground is permitted.
Why usable capacity can be lower
Water below a pickup point, trapped by the caravan’s angle or unavailable when one pump fails may remain in the tank. Gauges can be coarse or inaccurate. A controlled fill-and-draw test helps establish practical capacity.
Filling, draining and isolation
Locate and identify:
- each fill point and breather;
- tank selection or isolation valves;
- low-point drains;
- pump, strainer and filter;
- grey-water outlet and holding tank;
- any separate drinking-water tap.
Ask the manufacturer or seller for the plumbing diagram and operating instructions. On a used caravan, check for unexplained modifications, leaking fittings, damaged mounts and hoses that are unsuitable for potable water.
Weight and loading implications
Water weight changes payload and may alter axle or tow-ball loads depending on tank position. Full tanks can also affect handling. Use actual tank capacities and a weighbridge-based loading plan rather than assuming the location is neutral.
Questions to ask before buying
- What is the nominal and measured usable capacity of each tank?
- Which outlets draw from which tank?
- Can tanks be isolated if a line leaks?
- Is there a grey-water holding tank, and how is it emptied?
- Are the tank, filler, hose and fittings approved for drinking-water contact?
- How are tanks supported and protected underneath?
- When were filters and hoses last replaced?
For a used caravan, include the water system in a broader inspection rather than testing only the tap. A seller should be able to explain the setup and provide manuals where available.
Check local wastewater requirements
Grey-water handling requirements depend on the place and the facility. Check the current campground or land-manager rules before arrival. For Western Australian examples, see WA Health: wastewater dump points and the WA nature-based parks guidelines.