Sorry just deleted what I wrote be a mistake so round two.
I came up wi the idea after seeing someone doing the same on youtube but the only difference for me my van moves where the van was a static caravan.
My vans roof will floor mum garden when it rains, so what a waste of water. The water can be made to run off down the back into a small-large item filter, then down to a pre tank
3 stage filter, cost £27 the filter will remove 98% of crap. also, its easier for me because I do not drink the van's water.
to help the water a bit more, can add inline filters, these are small and cheap at about £20 for a set of 3 and will last about 2 years. for full drinking water.
using something like this would work well and have good water on tap for cooking.
amazon the overall cost would be around £95 if i went for the inline too.
if you was to go for a top pro thing i think the cost is around £800.
thing is, there's loads of way you can go about making a filter system, taking a fish pond water filter and adding the active charcoal and carbon filters yourself, there's loads on youtube about it and oddly the £800 system works in dead the same way.
Funny, the fish pond filter system are also the same as human water filters just with a different medium.