Water tanks for your caravan or RVs come in various holding capacity sizes. They can range from 55 litre (11.5 gallon) up 127 litre (28 gallon), are normally black in colour, and the plastic type are usually covered by a bash plate to prevent puncture.
Water tanks also come in stainless steel and as there is a need to conserve weight when towing these are less likely to be used in caravans.
Some RV’s have one water tank and others come with several. Usually there is one separate tank specifically for drinking water and at least two others for shower facilities, washing up and general washing.
Where there are several tanks, they are normally joined by a piece of hose or plumbing between each to allow for multiple filling and it may be worth considering installing a shut off inline valve, which is similar to a tap, between each tank.
The purpose of this is to avoid loosing the water from all tanks in the unfortunate event that one of the tanks is punctured. Another purpose is that you can avoid filling all your tanks if you do not need to do so for say short trips, although care should be taken when doing this to ensure the 12V pump operates from the useable tank(s).
If not already installed, tank gauges are very useful to monitor the water level of the tanks. See related article on filling tanks.
An ‘accumulator’ tank is a tank with a bladder inside. These are often used in motorhomes. One side of the bladder is pressurised by compressed air and the other side contains water. The flow of water, with a 12V pump, is smoother due to the constant pressure thereby eliminating ‘water hammer’.
When filling a caravan drinking water tank use a food grade hose (often white in colour) as filling the tank with a garden hose will make the water taste somewhat ‘plastic’.
‘Grey Water’/ ‘Black’ Water Tanks
Although not as prevalent here in Australia, some campgrounds and National Parks are becoming more concerned with the environment and do not want ‘grey water’ dumped onto the ground.
Motorhomes, fifth wheelers and some campervans have three water tanks. One for fresh water, one for toilet sewage (known as ‘black water’) and one grey water for water collected from other drains (eg: sink/shower).
Regular use of the shower facility and/or sink will often see the ‘grey water’ tank fill up sooner than say the ‘black water’ tank.
With the demand to retain fresh water some innovators have installed a 12V pump to use the ‘grey water’ to flush the toilet.
There is a diverse range of water pumps for RV’s.
Hand operated pump – this is located on the sink and is a plunger type, operated by hand pumping in an up and down motion. There is also a model called Fynspray Hand Pump which has a black moulded nylon body with a chrome plated brass handle and swivelling spout.
Foot pump – this is designed for flush fitting on the floor. It is operated by depressing and lifting your foot in a pumping action. It is often located on the floor in front of the sink.
12V pumps – there is a range of either SHURflo or Flojet pumps varying in size and flow capacity from 4.3 litres per minute to 12.5 litres per minute. Some promise smooth running without the need for an accumulator tank and are able to run dry without any harm to the pump. These pumps can be located under the sink or refrigerator and are connected to the 12V power system and the water tanks.
Most pumps have a built-in pressure switch that activates the pump once the tap is turned on. There is normally an electrical on/off switch located near the sink which also must be turned on as this activates the power supply for the pump.
12V pumps are very useful when you are not connected to mains pressure. They are also good for access to your filtered drinking via a separate tap located on the sink and drawn from a separate drinking water tank located under the RV.
Some ATV or off-road designed caravans have a separate 12V pump enabling them to pump water from creeks directly into their shower water tanks via the filler on the side of the van.
Pump Control Valves
Some motorhomes have a set up where the main pump can be isolated from the system to allow water to be pumped from an external source or between tanks.