What length of water hose?

I normally say it should be about a foot longer than the distance from Tap to 6 inches into the inlet point.  

Tonight I will be a well behaved A B M  and say that my hose is approximately 10 feet / three metres long  

I started off with one of 25 meters, 95 percent of the time that was too long. Due to damage I have cut it down to about 10 meters. In this country I doubt you would need anything longer. (CLs excepted) I believe the flat hose on a reel can be bought in two lengths, 15 or 25 meters. If I was replacing mine I would still go for 25 meters just for that odd occasion when the tap is a bit more distant.

peedee

We switched in March 2019, and have only used it on about 30 different sites so far. When caravanning we took two joinable lengths of 10 and 8 metres for use on service pitches. I decided to only pack the 10 metre length and so far that has been sufficient both in the UK and France.

Law of Sod: Whatever length is selected it will be a metre too short.

I use a BRUNNER 15M ROLL-ON HOSE REEL WITH FLAT FOOD GRADE HOSE They are shown on Leisure shop direct for £27.95 

This type of flat hose can be unrolled to the length required leaving the rest still rolled. It’s slightly slower water flow but I’ve never found this much of a disadvantage over the advantage of not having to unroll it all and the ease of storage.

I’ve got one of those 30m expandable hoses which mostly does the job and takes up little space when stored. However, they don’t seem to have a long life and will readily split if you just look at them the wrong way. X-hose and Hoselock are the brands to avoid.

Well there you are - suggestions range from 3 metres to 30 metres of hose. That's perhaps why every self reliant Dutchman I ever met was carrying a plastic watering can - and many Dutch campsites helpfully provide them by every water tap. 

Ah well Eurortraveller the OP was asking for what hose length to carry,  so I never gave any thought to talking of what system I use --> my most recent watering can was bought at the garden centre near to Ferry Meadows Club Site after I had a slight accident with the original -- the wind moved it and I put 750k ( one wheel ) over it and flat watering cans are not a lot of use are they