Microhydro Basics

How does microhydro work?

Water falls through a pipe to a turbine, which spins a generator. The power available depends on two things: head, the vertical drop between intake and turbine, and flow, the volume of water moving. More of either gives more power.

Because streams run day and night, a small system can supply steady energy with relatively little storage. The catch is that flow changes with season and drought.

Because flow is steady, microhydro often needs a smaller system than solar for the same daily energy, but it needs the right site. A small stream with plenty of drop can be better than a larger one that is flat.

How do I assess my site?

Measure the drop from the intake to the proposed turbine location and the flow in the driest part of the year, not after a rain. Note the distance from the turbine to where the power is used, since long wire runs lose energy.

Ask your county conservation district, NRCS field office or a qualified hydro installer about measurement methods. Photograph the stream through the seasons and record observations over time.

Check how the system will connect to your loads. Long wire runs lose power, and the best site for the turbine may not be the best site for the house, so ask a designer how to balance the two.

• Vertical drop between intake and turbine.
• Lowest seasonal flow, not peak flow.
• Pipe route, access and distance to the loads.

Who owns the water, and what permits apply?

This is the question that can end a project. Water rights, diversion limits and permits vary widely by state and sometimes by stream. Owning land next to a stream does not always mean you may divert or use its water for power.

Ask your state water resources agency, your conservation district and your county or town office what approvals apply. Ask about stream protections, fish passage, wetlands, dam safety and any review for changes to a waterway. Do not begin work until you have answers in writing.

Write down all the dates, contacts and answers from agencies in one file. Rules can change over time, and a paper trail helps if you later need to prove what you were told and when.

What are the environmental concerns?

Taking water from a stream can harm fish, insects and downstream users, especially at low flow. Intakes need screens and a plan to leave enough water in the channel. Disturbing banks risks erosion and sediment.

Agencies may require specific measures. Ask your state wildlife or environmental agency what they expect, and work with a qualified designer.

What does a system involve, and what does it cost?

Typical parts are an intake, a pipeline called a penstock, a turbine and generator, controls, wiring and, for off-grid use, batteries and an inverter. The pipeline and civil work often cost more than the turbine.

Cost categories include design, permits, intake, pipe, turbine, electrical work, installation, maintenance and monitoring. Get quotes that list what is included, and ask installers about similar projects.

What safety and upkeep should I plan for?

Moving water, wet footing, pressurized pipe and electrical equipment all carry risk. Floods can destroy an intake in an hour. Leave design, electrical and civil work to qualified people, and never work alone near fast water.

Plan regular cleaning of the intake screen, inspection of pipe and joints, and checks of wiring and controls. Keep a log.

Make a plan for floods and ice. Intakes and pipes can be damaged by high water, debris and freezing, so ask how the design handles them and how you will shut it down safely before a storm.

What should I do first if I have a stream?

Start with a conversation, not a purchase. Contact your state water resources agency and conservation district to ask about water rights, permits and stream protections. Write down their answers and the names of the people you spoke with.

Then measure drop and flow over a year and keep photographs. Talk with a few installers who have built systems on similar streams, and ask to visit one. Ask what the system produced in the driest month and what it cost to maintain.

Consider also whether a smaller step makes sense, such as a hydraulic ram or a small turbine for a single building. Starting small lets you learn the stream, the rules and your own tolerance for upkeep before a bigger investment.

Last reviewed: November 12, 2026. Written by the Homestead & Small Farm Editorial Team. See our editorial policy.