Boondocking calculator
How many days can you dry camp before your fresh water runs out or your gray or black tank fills? Enter your tank sizes and how your group uses water.
Find your RV’s tank sizes on its spec page, or in your owner’s manual.
How this is estimated
Tank sizes are the manufacturer’s published capacities. Daily use is an estimate per person: sinks and dishes 1–3 gal, toilet flushing 0.5–1.5 gal, drinking and cooking 0.5–1 gal, and 2–8 gal per shower, depending on the water-use setting. Sinks and showers drain to the gray tank; toilet water plus about 0.25 gal of waste per person goes to the black tank. “Mostly park or vault toilets” counts a quarter of normal toilet use. Real use varies a lot, and tank gauges are often inaccurate, so plan to leave a margin. Battery power and propane can also limit a trip and aren’t included.
Common questions
How many days can you boondock in an RV?
It depends on your tank sizes, the number of people and how carefully you use water. A couple with 40 gallons of fresh water using it carefully can often last 5 to 7 days; a family of four showering daily and using water like at home may last only a day or two.
Which tank runs out first when boondocking?
It depends on the RV. Many newer trailers have a gray tank larger than the fresh tank, so fresh water runs out first; RVs with a small gray tank fill it first, because sinks and showers drain into it. The calculator shows which of your tanks is the limit.
How much water does one person use per day when dry camping?
Roughly 2 to 5 gallons per person per day when being careful, and 10 gallons or more with daily full showers.