Have you considered Rainwater ...

Have you considered Rainwater harvesting?

If you could construct a storage tank for the rain water to run in to. Then the water you start with would not contain lead. Plus with a simple percolation filter where the water from the tank flows through a sand bed into barrels ready to transport.

The sand filter could be make using two barrels half filling a barrel with sand and drilling a very small pin hole in the bottom to allow th ewater to drip out into another barrel. . .

Another way I can suggest is evaporation type system. Using the heat of the sun to make vapor and then collecting the vapor on a condensing surface. I would find an area with a gentle slope in the sun light. lay a sheet of plastic on the ground with another 50cm above making sure they dont touch. Then collect the droplet as they role down the above sheet.

I am an inventor so these are just ideas and not tried and test industry solutions. But if you want me to explain in more detail let me know.