Nano-hydro system (10W @ 12V or USB 5V, only 23 oz) charging a 12V 7Ah sealed lead-acid battery from a steep stream.

Backpacking hydro power system by Tactical Woodgas

This ultra-light hydroelectric power generator provides up to 10W (12V at 0.83A or 5V at 2A) to supply your camping or offgrid power needs by harvesting the free energy of moving water. When dry the unit weighs 23 ounces.

The unit includes the water turbine with 5V/12V output, two 15 foot flat hoses, and a carrying bag that doubles as the water funnel. A wire stiffener is included; insert this into the funnel mouth with the drawstring to keep the funnel mouth open.

The input needs to be at least 10 feet higher than the mouth of the funnel to make power.

Place the funnel in a reasonably steep stream to gather power from natural water flows.
Connect the funnel to the top of your rain gutter downspout to gather power from rain.
Connect the funnel to a 1 inch hole in the center of a tarp that is suspended off the ground at least 10 feet to gather power from rain.
Set aside the funnel and hoses and connect the hydro turbine to your garden hose to gather power from your home water pressure.