A 40-gallon RV fresh water tank lasts 2–4 days for 2 people with normal use, or 5–8 days with strict conservation. The biggest variable is shower length: a standard 8-minute shower uses 16 gallons, while a navy shower uses only 3–4 gallons.
- Normal use (2 people): ~20 gal/day = 2 days on a 40-gal tank
- Moderate conservation: ~10 gal/day = 4 days
- Strict conservation (navy showers, minimal sink): ~5–7 gal/day = 6–8 days
- Showers account for 50–70% of total RV water consumption
- Adding a third person reduces duration by roughly 30–40%
| Conservation Level | Daily Use (2 ppl) | 40-gal Duration | 60-gal Duration |
|---|---|---|---|
| Normal | 18–22 gal | 2 days | 3 days |
| Moderate | 10–14 gal | 3–4 days | 4–6 days |
| Strict | 5–7 gal | 6–8 days | 9–12 days |