How big a microhydro plant do you need to power your house?

You'd need to work out your overall energy consumption in kilowatt hours per day.

Your usage probably has peaks and troughs, and for a microhydro, you want it to be demand-responsive, so it uses large amounts of water when you need most power, then throttles back to almost no useage when your power demand is very light.

If you can't do this, you end up running at a water usage enough to supply your peak power demand *all the time*, and wasting a lot of water.

With a throttling/adaptive system, after you know the system's efficiency, you can work out the amount of energy needed from kilowatt hours to joules, with one kWh equalling 3.6 million joules (3.6 MJ).

You can then work out how much volume of water you need for the head of water you have.

I don't have the hydraulic comps at hand, but your local High School/College/Polytechnic's Science/Engineering Dept. can probably help.

Best case, they may take on your question as a class project.