Whale Water System: Pump Service, Filter Replacement & Winterisation

What This Is

Whale water systems are fitted to a large proportion of UK motorhomes and caravans. This guide covers all owner-level maintenance tasks to keep the system running reliably.

Tools & Parts Required

Step-by-Step Instructions

1. 1

   Locate the Whale water pump (typically under the kitchen sink or in a service locker) and the inline filter — usually a clear cylindrical housing in the supply line before the pump.

2. 2

   Turn off the water pump. Drain pressure by opening a tap. Place a bucket under the filter housing. Unscrew the housing anti-clockwise. Remove the old filter cartridge and discard. Rinse the housing, insert the new cartridge, and reassemble. Replace filters every 12 months.

3. 3

   At the start of each season, sanitise the water system. Add one Milton sterilising tablet or 5ml of food-grade hydrogen peroxide per 10 litres of tank capacity. Fill the tank and run water through every tap until you can smell the sanitiser. Leave for 30 minutes, then drain and flush with fresh water.

4. 4

   If the pump is noisy, runs continuously, or delivers low pressure, it may need servicing. A Whale service kit contains replacement diaphragms and valves. Remove the pump head, replace the diaphragm, and reassemble following the kit instructions.

5. 5

   Inspect all jubilee clips on hose connections throughout the system. Tighten any that have loosened. Check hoses for kinking, cracking, or perishing — replace any that show deterioration.

6. 6

   To winterise: drain the fresh water tank completely. Open all taps to drain the pipework. Use a 12V pump to blow compressed air through the system from the tank inlet, opening each tap in turn until no water flows. Add food-grade propylene glycol antifreeze if the vehicle will be stored in freezing conditions.

Common Mistakes to Avoid

When to Call a Professional