I became obsessed with getting water when we first started wild camping in Spain some years ago, it was ridiculous as water was available everywhere, but I had to keep my tank full and all the 5 litre bottles I had,. had to be full. I'm over that now and water is easy to get on beaches,from the cold shower facilities, it's town water so is OK for the tank, we buy bottled water to drink neat and only costs pennies, cemeteries are a good source as are mountain fuentes and I have seen vanners catching the run off from their vans on rainy days,try petrol stations,public toilets ,desert wells,car washes usually have taps, I always ask before taking water as someone has to pay for it somewhere.