A frozen pipe in a campervan is not just inconvenient — it can burst, causing water damage to your conversion. Here is how to stop your drains and pipes from freezing in UK winter conditions.
Verdict
For occasional UK winter trips: drain down the system when freezing is forecast and pour food-grade propylene glycol antifreeze down the drains. For full-time winter living: wrap pipes in Armaflex insulation, add trace heating to the external sections, and keep the grey water tank internal. The £20-30 spent on insulation and antifreeze is cheaper than repairing a burst pipe (£200-500 for a full pipe replacement).
The Freeze Risk in UK Vans
UK winter temperatures regularly drop below freezing:
- Average December low: 2°C (South) to -2°C (Scotland)
- Record lows: -10°C to -15°C across the UK
- The danger zone: Pipes freeze at -2°C to -5°C if they are exposed to outside air The worst situation: you park the van overnight, the temperature drops to -5°C, and the water in your drain pipes or freshwater lines freezes by morning. If you turn on the tap and the pump pushes against a frozen block, the pipe bursts at the weakest point — usually a joint or a bend.
Where Freeze Happens
| Location | Freeze Risk | Why |
|---|---|---|
| External fresh water fill point | Very high | Directly exposed to outside air |
| Grey water tank outlet | Very high | Under the van, exposed |
| Sink drain pipe (under sink) | High | In an unheated cabinet against an outside wall |
| Fresh water pipes under the van | High | Directly exposed to road air and wind chill |
| Internal pipes (in the cabinet) | Medium | Near exterior walls, no heat circulation |
| Internal pipes (behind panels) | Low | Warmed by the van's heating |
| Whale / manifold fittings | Medium | The weakest joints freeze and crack first |
Insulation
Insulation is the first line of defence.
| Material | R-Value per 25mm | Cost | Best For |
|---|---|---|---|
| Armaflex closed-cell foam | R-1.1 | £4/m (15mm wall) | Wrapping pipes under the van |
| Pipe lagging (split foam) | R-0.8 | £2/m | Internal pipes in cabinets |
| Reflective foil bubble wrap | R-1.0 | £3/m | Wrapping tanks |
| Self-adhesive foam tape | R-0.5 | £3/roll | Sealing gaps around pipes |
| Installation: Wrap all external pipes with Armaflex (15mm wall thickness). Secure with zip ties or PVC tape (not duct tape — it degrades). Internal pipes benefit from pipe lagging but the most important step is sealing any drafts around the pipe entry points — cold air flowing over a pipe freezes it much faster than still cold air. |
Trace Heating
For vans that live in freezing conditions (Scottish winter, mountain trips), trace heating is the answer. Trace heating is an electric heating tape that wraps around pipes and maintains a temperature above freezing. How it works:
- Self-regulating trace heating tape (e.g., Heat Trace UK HTSR-10, £5/m)
- Wired to the 12V system (12V trace tape draws 10-15W per metre)
- The tape senses the pipe temperature and heats up when it drops below 3°C
- Wrapped around the pipe under the insulation Installation:
- Wrap the trace tape in a spiral around the pipe (not tightly — allow for expansion)
- Cover with Armaflex insulation (trace tape without insulation wastes 80% of the heat)
- Wire to a 12V circuit with a 5A fuse
- The tape draws 10-15W per metre — a 2-metre run uses 20-30W, which is 1.7-2.5Ah per hour Cost: £10-20 per metre for the tape, plus £10 for a thermostat controller.
The Drain-Down Method
The simplest freeze protection: drain the water system when freezing temperatures are expected. Quick drain-down (5 minutes):
- Open all taps (hot and cold)
- Open the low-point drain valves (under the van)
- Pump runs dry — turn off the pump
- Pour 1L of food-grade antifreeze (Propylene glycol, not car antifreeze) down the sink and shower drains
- Remove the external fill hose and store inside Full drain-down (20 minutes):
- Complete the quick drain-down steps
- Remove the shower head and hold it below waist height to drain the riser pipe
- Disconnect the pump inlet hose to drain the pump body
- Blow through the pipes with a tyre pump (12V tyre inflator) to clear standing water
- Pour antifreeze into the sink and shower drains — antifreeze has a lower freezing point and stays liquid
Food-Grade Antifreeze
| Product | Type | Freeze Protection | Price | Availability |
|---|---|---|---|---|
| Whale Winter Sanitisation Kit | Propylene glycol | -15°C | £8 | Caravan shops, Amazon |
| Sierra Antifreeze for Caravans | Propylene glycol | -20°C | £10 | Halfords, caravan shops |
| Fernox GLY-01 | Propylene glycol | -15°C | £12 | Plumbers merchants |
| Do not use: Ethylene glycol car antifreeze (toxic, tastes sweet — pets and children will drink it). Do not use screen wash (it leaves a residue that clogs taps and pumps). |
The "Drip the Tap" Hack
If you are in the van and temperatures drop below -5°C, let the taps drip slowly. Moving water does not freeze as easily as standing water. A slow drip (one drip per second) keeps the water in the pipe moving and prevents a freeze block. The water drains into the grey water tank — this is fine for one night. How much water: One drip per second = about 1L per hour. Not ideal but it beats a burst pipe.
Winter Conversion Design Tips
If you are building a van for winter use:
- Pipes in the floor: Only if there is insulation above and below the pipes. Bare pipes under the van between the floor and the underslung protection will freeze.
- Pipes in the cabinet: Route pipes through heated interior spaces. Keep them away from exterior walls.
- Heated cupboard: Add a small 12V heating pad (£15, Amazon) inside the cupboard that contains the water tank and pipes. Thermostatically controlled to 5°C.
- Internal grey water tank: An internal grey water tank (under the seat or in a cabinet) eliminates the under-van freeze risk. It takes up storage space but it never freezes.
