Fresh Water Tank
The onboard tank that holds potable water for sinks, shower, and toilet flushing. Capacity matters for boondocking; less relevant on full hookup.
Also called: fresh water tank, potable water tank, FW tank
The fresh water tank is the onboard tank holding potable water for the RV’s sinks, shower, and toilet flushing. Capacity matters most for boondocking trips; for full hookup camping, you’re connected directly to the campground spigot and the tank is just a backup.
Typical capacity by RV class
| RV class | Fresh tank capacity |
|---|---|
| Class B camper van | 15-30 gal |
| Class C motorhome | 40-80 gal |
| Class A motorhome | 60-100 gal |
| Travel trailer | 30-60 gal |
| Fifth wheel | 50-90 gal |
Usage estimates
For two people on a boondocking trip with conservative use:
- Drinking + cooking: 2-3 gal/day
- Sink/dishes: 3-5 gal/day
- Toilet flushing (low-flow): 1-2 gal/day
- Quick showers (Navy style): 4-8 gal/day per shower
Realistic daily consumption: 10-18 gallons for two people.
A 50-gallon fresh tank gives 3-5 days off-grid for two. A 30-gallon tank gives 1-2 days.
What “winterized” fresh tank means
When a rental is winterized, the fresh water system has been drained and antifreeze added. Most rentals are de-winterized in spring and re-winterized in fall. Don’t rent a winterized rig in spring before it’s been flushed — the antifreeze tastes terrible and lingers.
How to extend fresh tank capacity
- Use the campground bathhouse when available
- Bring extra water in jugs (1-gal jugs work, but 7-gal Aquatainers are better)
- Refill at potable water spigots at most state parks and some forest service campgrounds
- Filter rainwater or stream water is unreliable for drinking but works for dishes and toilet