I use rainwater, I have 4 IBC's (4000L) connected to about 80m of guttering on a barn. The downpipes have debris stoppers placed in them. The roof is not the cleanest and the water in the tanks reads 30-35. The tanks are situated in the the upstairs of the barn and so it gravity feeds into the van. In the van the water runs through a 3x20"filter unit from VYair products, then twin 11L DI's. Have been using this setup for just over 12 months, not changed the resin - TDS still reads zero. I have never run out of stored water. However my usage of water each week varies, some weeks its 500L another week it could be 2000L.
I will get some photos on for you of the tank setup in the next couple of days when I go top back up.