How to Build a Small-Scale Hydropower System in Your Backyard


I have been interested in renewable energy for quite some time. With electricity prices rising and a desire to be more self-sufficient, I decided to research building a small-scale hydropower system in my backyard. Hydropower harnesses the energy of flowing water to generate electricity. While large hydropower dams require massive civil engineering projects, small-scale hydropower can be achieved with fairly simple DIY systems. In this article, I will walk through the complete process I followed to create a backyard hydropower system to offset some of my home's electricity usage.

Assessing if Hydropower is Right for Your Property

The first step is determining if your property has the right conditions for a DIY backyard hydropower system. There are several key factors to consider:

Water Source

First and foremost, you need access to flowing water on your property, such as a stream, creek, or other waterway. The vertical drop and flow rate of the water will impact the potential power output. Generally, a drop of at least 2 feet and a flow rate over 2 gallons per minute is recommended for a small backyard system.

Head vs Flow

For hydropower, head refers to the vertical drop of the water, while flow refers to the water volume per minute. Both head and flow contribute to power potential. More head or more flow will allow more electricity generation. However, most backyard systems are limited by what naturally exists on the site.


Using water on your property for hydropower will likely require permits from local authorities. Research the laws in your area and what is needed for a small low-impact system. Permits help ensure the environment and other water users are not negatively impacted.

Site Layout

Consider the layout of your property and where different components of the system can be located. The water intake, turbine, and powerhouse all need to be relatively close together. Is there space to route the penstock piping?

Grid Connection

To use the electricity from the hydropower system, you'll need to connect into your home's electric grid. Consider where this connection will be made and how the power will be regulated and monitored.

If your property has the right natural conditions and space for the system components, a backyard hydropower project may be feasible.

Choosing a Turbine

If you determine your site has potential, the next step is choosing a turbine to convert the water's flow into rotational energy. Two main options exist:

Impulse Turbines

Impulse turbines use the velocity of water to turn the runner and shaft. Common impulse turbine designs include Pelton wheels.

- High efficiency, up to 90%
- No suction head required
- Can accommodate high heads

- Require precise nozzle alignment

Reaction Turbines

Reaction turbines use water pressure and the rate of flow to propel the runner. Common reaction turbines include Francis turbines and propeller turbines.

- Handle large volumes of water flow
- Operate with low heads

- More complex design

The type of turbine chosen depends on the head and flow levels available at your specific site. I decided on a crossflow impulse turbine for my backyard system since I have relatively low flow but high head.

Sizing System Components

Once you know what type of turbine to use, the piping, generator, and other components need to be sized accordingly.


The intake directs water from the stream into the system's penstock piping. It must be large enough to avoid restricting water flow but small enough to avoid catching debris.


The penstock is the piping carrying water from the intake to the turbine. This should be sized based on the desired flow volume. Larger diameters allow more water to pass through with less friction loss.


Match your turbine size to the available head and flow. Too small, and the maximum power cannot be captured. Too large, and the turbine will spin uselessly with low efficiency. Consult turbine performance charts.


The generator or alternator converts the rotational energy into electrical energy. It must be properly sized for the expected rotation speed and power output from the turbine.


Most DIY systems use a battery bank to store energy. Thus, you need an inverter to convert the generator's AC power into usable DC current for charging batteries.

Properly sizing all components ensures an efficient backyard hydropower system.

Civil Works and Construction

With the right property conditions and system components selected, it's time for the civil construction phase. This includes:


The intake structure is situated in the waterway. Make sure it is stabilized, filters debris, and channels the diverted water flow.


Lay the penstock piping from the intake to the turbine location. Bury piping to prevent freezing if necessary. Include an access junction box for maintenance.


The powerhouse contains the turbine, generator, inverter and controls. Build a secure waterproof housing or shed for the equipment.


The tailrace returns water to the stream after passing through the turbine. It must channel water away to prevent backflow interference.

Erosion Control

Introducing structures into waterways can cause erosion. Implement stones, revegetation or other control measures as needed.

For my system, I dug a trench to bury 200 feet of 6-inch HDPE penstock pipe from the intake to my shop. The shop now serves as a convenient powerhouse location.

Electrical System and Controls

The electrical system includes the generator, inverter, wiring, breaker panel, batteries, and monitoring controls.


The generator produces 3-phase AC power. Rectifiers convert AC to DC for battery charging.


The inverter takes DC battery power and converts it back to usable AC electricity. Grid-tie inverters synchronize to main grid power.


Deep cycle lead-acid batteries are commonly used for small hydropower systems. Lithium-ion batteries have benefits but higher cost.

Breaker Panel

The breaker panel connects the inverter output to your home's electric system and allows you to tap into the hydropower or main grid as needed.


Controls regulate the turbine speed, monitor the system, and optimize power production. Automated controllers prevent damage from over-generation.

For safety, all wiring must follow electrical code standards. It is also crucial the system includes proper switching between the hydropower system and the main electric utility grid.

Operating and Maintaining the System

Once constructed, the hydropower system can generate clean renewable electricity for decades with proper operation and maintenance. Key aspects include:


Periodically inspect all structures, components, piping, and electrical systems for damage or clogging by debris. Replace worn parts as needed.

Gear Oil

Turbines with enclosed gearboxes require periodic gear oil changes to reduce wear and extend operational life.

Bearing Lubrication

Lubricating bearings on the turbine shaft and generator maintains smooth performance and prevents excess wear.

Battery Care

Test batteries regularly and replace as they lose capacity. Proper maintenance improves battery bank lifetime.

Water Flow

Monitor water flow and turbine function. Adjust as needed to maximize power production throughout seasonal variations.


All equipment and wiring should be properly grounded and installed to relevant electric codes to prevent electrocution risk.

Routine inspections, maintenance, and safe operation will allow your backyard hydropower system to function as a renewable energy asset for many years. The upfront investment of time and money pays dividends through decades of clean power production.


Constructing a small-scale hydropower system on your property is an involved but rewarding project. With proper site conditions, equipment sizing, installation, and maintenance, a home hydropower system can provide supplemental electricity from renewable energy for the long term. Remember to research permitting requirements and adhere to all safety guidelines throughout the process. With patience and hard work, you can harness the flow of water on your land to produce your own local, sustainable electricity.