How it's calculated
Fresh water days = fresh tank (L) ÷ (people × 11 L a day)Grey water days = grey tank (L) ÷ (people × 9 L a day)The lower of the two is how long you can stay before refilling or emptying
Grey water is the waste from sinks and showers. It is lower than fresh water use because drinking water and cooking water do not all end up in the tank.
Worked example
2 people with a 100 litre fresh tank and a 90 litre grey tank have 4.5 days of fresh water and 5.0 days of grey water, so the fresh tank sets the limit.
Assumptions
- 11 litres of fresh water and 9 litres of grey water per person per day are planning figures for careful use: drinking, cooking, washing up and a quick wash. Showers use far more.
- Toilet cassettes and black water are not included.
- Empty grey water only at a dump station. Never on the ground or into a stormwater drain.
Common questions
How long does 100 litres of fresh water last in a campervan?+
For two careful users at 11 litres each a day, about four and a half days. Showers and washing clothes shorten that a lot.
Where can I empty grey water in New Zealand?+
At a dump station. Many holiday parks have one, and councils run public ones in many towns. Never empty grey water onto the ground or into a stormwater drain.
Which tank runs out first?+
Whichever is smaller for your use. Grey tanks are often smaller than fresh tanks, so check both rather than only the fresh water gauge.
Related guides
More road trip calculators
Plan it in KiwiCamping
Find the stops, then do the maths.
KiwiCamping is free to download for iPhone. Bookable holiday parks, stays and tours are free in the app. DOC campsites, huts, dump stations and the guides open with the Pass.