Macerator Pumps for Grey Water in Vans
A macerator pump lets you dispose of grey water through a small-diameter hose, rather than a gravity drain. Here is the honest guide for UK van builds.
How They Work
A macerator pump sits in your grey water tank (or inline) and grinds the water into a slurry, then pumps it through a 20mm or 25mm hose. This is the same technology used in boat and caravan waste systems. The pump can push water uphill and through a narrow hose — unlike a gravity drain that needs the tank to be higher than the outlet.
Why Use One
- Flat van builds: If your grey water tank is mounted under the floor (below the sink level), gravity will not drain it. A macerator pump lifts the water to the outlet.
- Discreet disposal: Pump grey water into a 5L portable container instead of draining onto the ground. Better for Leave No Trace camping.
- Long hose runs: Run the outlet hose to the side or rear of the van, wherever is convenient.
Best Options
| Pump | Price | Flow | Noise | Notes |
|---|---|---|---|---|
| Whale Gulper 220 | £90 | 25L/min | Moderate | Most popular in UK van builds |
| Johnson Aqua Jet | £75 | 20L/min | Quiet | Good for low-height installations |
| Jabsco 12v | £85 | 30L/min | Loud | High flow, industrial |
| Shurflo 2088 | £70 | 24L/min | Quiet | Budget option |
Installation Tips
- Mount the pump as low as possible (below the tank outlet if you can)
- Use 20mm push-fit hose (John Guest speedfit, compatible with all pumps)
- Fit a strainer before the pump (food scraps clog macerators)
- Wire through a switch (not the same switch as the water pump — you control it separately)
- Fit a non-return valve after the pump (prevents backflow when parked on a slope)
Pros and Cons
Pros:
- Allows under-floor tank mounting
- Cleaner disposal (pump into a container, not onto the ground)
- Flexible outlet positioning Cons:
- More complex than gravity (pump can fail)
- Noise — the Gulper 220 sounds like a wet vacuum
- Power draw (runs on 12v, 5-8A)
- More components to freeze in winter
Macerator vs Gravity
| Factor | Macerator Pump | Gravity Drain |
|---|---|---|
| Cost | £70-100 + hose | £20 (pipe + fitting) |
| Complexity | Medium | Low |
| Reliability | 3-5 years (pump lifespan) | Indefinite (no moving parts) |
| Installation | Flexible | Needs tank above outlet |
| Noise | Loud | Silent |
| Winter | Drain pump separately | Drain valve, no issues |
Verdict
Only install a macerator pump if you have to — meaning your tank is below the sink level. If you can route a gravity drain from a higher tank, do that. Simpler, cheaper, and never breaks.
