How often should I service my motorhome?

Most motorhomes require an annual habitation check and a chassis/engine service every 12 months or 12,000 miles, whichever comes first. The habitation check covers gas, electrical, water, and damp systems and should be carried out by an NCC Approved Workshop.

What is a habitation check on a motorhome?

A habitation check is an annual inspection of all the living systems in a motorhome or caravan, including gas appliances, 12V and 230V electrical systems, water pump, heating, and a damp survey. It is recommended by the NCC and most manufacturers.

How do I find a Gas Safe engineer for my motorhome?

Use the Find a Repairer tool on MotorhomeHelp to search for Gas Safe registered engineers near your postcode. All gas work on motorhomes, caravans, and campervans must be carried out by a Gas Safe registered engineer.

How do I check for damp in a motorhome?

Damp in a motorhome is checked using a damp meter (also called a moisture meter). Key areas to test include the roof corners, window frames, floor edges, and rear panel. Readings above 15% on a damp meter indicate moisture ingress that needs investigation.

How do I winterise my motorhome?

Winterising a motorhome involves draining the fresh water tank, water heater, and all pipes, blowing out the system with compressed air or using food-safe antifreeze, disconnecting the leisure battery or connecting a trickle charger, and covering the vehicle. Full step-by-step instructions are available in the Winterisation guides.

Easy

Whale Watermaster Pump: Priming, Pressure Faults & Winterisation

Everything you need to know about the Whale Watermaster submersible pump — priming after storage, diagnosing low pressure and no-flow faults, and correct winterisation to prevent frost damage.

30–60 minutesEasy

What This Is

The Whale Watermaster is a submersible 12V electric water pump used in the fresh water tanks of many UK caravans and motorhomes. It sits directly in the fresh water tank and pushes water through the system when activated by the control panel switch or an automatic pressure switch. The pump is self-priming when submerged but requires correct installation and maintenance to deliver consistent pressure. Whale also produces an inline version (the Whale Gulper) for waste water, and a separate pressure accumulator (the Whale Accumulator Tank) that reduces pump cycling and smooths water pressure. This guide covers the submersible Watermaster pump specifically, though many of the diagnostic principles apply across the range. The Watermaster is a robust and long-lived pump when properly maintained. The most common issues are air locks after winter storage, blocked inlet filters, and worn impellers after several years of use.

Tools & Parts Required

Crosshead screwdriver
Adjustable spanner
Small bowl or bucket
Clean cloth
Caravan-safe antifreeze (propylene glycol based — NOT ethylene glycol)
Multimeter (for electrical fault diagnosis)
Torch or head torch

Step-by-Step Instructions

1
Locate the fresh water tank — usually under a seat, in a locker, or beneath the floor. The Watermaster pump will be visible as a cylindrical unit submerged in or attached to the tank, with a 12V cable and a water outlet pipe.
2
PRIMING AFTER STORAGE: If the pump runs but delivers no water, it has an air lock. Fill the fresh water tank with at least 10 litres of clean water. Switch the pump on and open the cold tap furthest from the pump. The pump may run noisily for 30–60 seconds while purging air. Do not run the pump dry for more than 2 minutes — this can damage the impeller seal.
3
If priming does not resolve the issue, check the pump inlet filter. The Watermaster has a small mesh strainer at the base of the pump body. Remove the pump from the tank (disconnect the outlet pipe and 12V connector first). Unscrew the filter cap and rinse the mesh under clean water. Refit and reinstall.
4
Check the 12V supply to the pump. Use a multimeter set to DC Volts. With the pump switch on, probe the pump connector — you should read 12–13V. If you read less than 10V, there is a wiring or fuse issue rather than a pump fault. Check the fuse in the 12V distribution board (typically 5A or 7.5A for the water pump circuit).
5
If the pump hums but does not pump water, the impeller may be jammed with debris or limescale. Remove the pump from the tank. Unscrew the pump body end cap (usually 4 screws). Inspect the impeller — it should spin freely by hand. Clean any debris and descale if necessary with a citric acid solution. Reassemble and test.
6
LOW PRESSURE DIAGNOSIS: If the pump runs but pressure is poor, first check that the tank has sufficient water. Then check all inline filters in the system — many motorhomes have a filter housing between the pump and the taps. A blocked filter is the most common cause of low pressure.
7
If you have a Whale Accumulator Tank (a small pressurised vessel, typically 0.5–1 litre, fitted inline), check its pre-charge pressure. The accumulator has a Schrader valve (like a tyre valve). With the water system depressurised, check the air pressure — it should be 0.5–0.7 bar. Top up with a bicycle pump if low. A waterlogged accumulator (no air charge) causes the pump to short-cycle — switching on and off rapidly.
8
WINTERISATION: Before winter storage, drain the fresh water tank completely. Run the pump briefly to clear water from the outlet pipe. Then pour 1 litre of propylene glycol antifreeze (caravan-safe, NOT car antifreeze) into the tank. Run each tap in turn until antifreeze flows — this protects the pump, pipes, and valves from frost damage. Do NOT use ethylene glycol antifreeze — it is toxic and unsuitable for potable water systems.
9
DE-WINTERISING IN SPRING: Drain the antifreeze from the tank. Fill with clean water and run each tap until the water runs clear and there is no taste of antifreeze. Flush the hot water system separately. Sterilise the fresh water system with a proprietary caravan water steriliser (Milton fluid or Puriclean) before use.

Common Mistakes to Avoid

Running the pump dry — even briefly without water causes rapid wear to the impeller seal and can permanently damage the pump.
Using car antifreeze (ethylene glycol) in the water system — this is toxic. Always use propylene glycol-based caravan antifreeze.
Forgetting to check the accumulator tank pre-charge pressure — a flat accumulator causes annoying pump cycling and is often mistaken for a pump fault.
Not sterilising the water system after de-winterisation — antifreeze residue and stagnant water can harbour bacteria.
Ignoring the inline filter — a blocked filter causes low pressure that is often blamed on the pump.

Safety Warnings

Always isolate the 12V supply before removing the pump from the tank.
Never use ethylene glycol antifreeze in a potable water system — it is toxic.
Do not run the pump dry for more than 2 minutes — this causes permanent damage.
Ensure all water connections are secure before restoring power — a loose connection can cause flooding in the habitation area.

When to Call a Professional

If the pump motor burns out (strong burning smell, no operation even with correct 12V supply), the pump will need replacing. Whale Watermaster replacement pumps are widely available from caravan accessory suppliers. If you are unsure about any 12V wiring, consult a qualified auto-electrician or motorhome engineer.