How Far Can Electrical Current Travel Through Water?

Electricity’s ability to travel through water has fascinated scientists for over 200 years. In the early 19th century, experiments showed that water could transmit electric currents over long distances. This discovery paved the way for using rivers and oceans to carry electrical power between distant points.

However, the conduction of electricity through water also poses risks. Any time an electrical current flows through a conductor like water, there is potential for lethal shocks. Tragically, many deaths have occurred when people came into contact with electrified water bodies. Safety measures are crucial when working with electricity near water.

This article explores how far electricity can travel through water. We discuss the key physics principles, real-world transmission projects, safety guidelines, and future directions in this emerging field.

Physics of Electricity in Water

Electricity can travel through water because water contains ions that allow it to conduct electricity. Pure water is actually a poor conductor, but even tap water contains impurities like salts that enable conduction. When an electric current enters water, it flows as the motion of electrically charged particles called ions. The ions collide with each other and nearby water molecules, transferring energy in the form of heat and enabling the current to move through the water.

The electrical resistance of water is dependent on the amount of dissolved salts and particles it contains. Distilled water has very high resistance, while salt water is a much better conductor. In comparison to metals like copper which have free flowing electrons, water is still a relatively poor conductor of electricity. However, it conducts far better than insulating materials like plastic or rubber which have very few mobile charges.

Factors That Affect Distance

Several factors determine how far an electrical current can travel through water, including:

Water Purity

The purity of the water significantly impacts conductivity. Distilled or deionized water has very high resistance and does not conduct electricity well. On the other hand, impure water with dissolved salts and minerals is much more conductive.

Mineral Content

The types and quantities of minerals dissolved in the water affect conductivity. Water with higher concentrations of ionic compounds like salts, acids, and bases allows electrical current to flow farther.


Salinity measures the saltiness of water, and salty water with high salinity is an excellent conductor. Seawater has high salinity, allowing electricity to travel large distances easily.


Hot water has faster moving ions, reducing resistance and increasing conductivity. Electrical current can generally travel farther in hot water compared to cold water.

Experimental Results

A number of scientific studies have tested how far electrical current can travel through water under controlled conditions.

In freshwater pools, electrical current has been shown to travel 15-20 feet from its entry point. In saltwater pools, the distance is even greater at 25-30 feet.

The farthest electrical current has been documented to travel is just over 50 feet in saltwater conditions. This maximum distance was recorded in an experimental tank with a strong electrical source.

Typical currents in freshwater lakes and rivers may only travel 5-10 feet from their source before dissipating. But under certain conditions, experiments confirm electrical current can travel up to 50 feet and potentially farther.

Real-World Examples

There are several real-world instances where electrical currents travel substantial distances through water:

Undersea Cables

Undersea cables transmit power and communications signals across oceans and seas. For example, transatlantic communications cables that connect North America, Europe, and Africa are over 5,000 miles long. Electrical currents are able to traverse these enormous distances through the highly conductive ocean water.

Fish Electrocutions

Electrified shorelines used for predator control or behaviors studies can conduct electricity over 300 feet out into the water. This allows electrical current to spread over a large area and inadvertently shock or kill fish that swim by.

Lightning over Oceans

When lightning strikes over a body of water, the electrical discharge can travel through the conductive ocean for several miles. This explains why lightning can electrocute groups of fish or damage boats a considerable distance away from the actual lightning strike point.

Safety Concerns

Electricity and water can be a dangerous combination if proper safety precautions are not taken. There are risks of electrocution anytime electricity comes into contact with water, which is why it’s important to understand the hazards and avoid risky situations.

The human body is particularly susceptible to electric shock in water, as water is an excellent conductor of electricity. As little as 10 milliamps of electrical current at 110 volts can cause paralysis and lead to drowning. Even low voltage currents can trigger respiratory arrest or ventricular fibrillation, which leads to death.

To avoid electrocution, here are some important safety tips:

  • Never use electrical devices near a sink, bathtub, shower, or pool.
  • Don’t enter flood waters near downed power lines.
  • Use ground fault circuit interrupters (GFCIs) in kitchens, bathrooms, laundry rooms, and near pools.
  • Have an electrician inspect electrical systems near water sources.
  • Unplug appliances before handling them near water.

Exercising good judgment is key to staying safe around electrical currents in water. Avoid entering unfamiliar bodies of water where hazards may be hidden. If you see downed power lines, immediately notify emergency services. Supervise children closely near water at all times.


Understanding how far electrical current can travel through water has enabled several important applications:

Transmission lines
High voltage transmission lines are sometimes run underwater for crossing large bodies of water like rivers, lakes and oceans. Knowing the conductivity of water helps determine the type of insulation and safe distances needed.

Water conductivity sensors

Sensors that measure water conductivity based on electrical current are widely used for applications like environmental monitoring, measuring salinity, and checking water quality parameters.

Underwater electrical equipment
Equipment like subsea cables, oceanographic sensors, and remotely operated vehicles rely on the conduction of electricity through water. The maximum safe distances for transmission help guide engineering specifications.


While electricity can travel through water over long distances under ideal conditions, there are several limitations to be aware of:

Signal Attenuation

As electrical current travels through water, the signal becomes weaker due to resistance in the water. This attenuation increases over long distances, reducing the viable transmission range.


Electrical noise and interference from other sources can disrupt signals sent through water. This is especially problematic for sensitive data transmissions.


It can be expensive to set up equipment and infrastructure to transmit electricity through water over long ranges. The costs go up as distance increases due to higher power requirements and more robust cables needed.

Future Research

There are several promising technologies under development that could improve the transmission of electricity through water. Researchers are looking at new methods and materials that could enhance conductivity and enable longer transmission distances.

One area of focus is using graphene, a superconductive form of carbon, to coat underwater cables. Graphene is extremely thin yet very conductive, so coating submarine cables with graphene layers could potentially allow for lower-loss transmission over long distances. However, graphene is still expensive to produce at scale. More research is needed to find ways to manufacture graphene cost-effectively.

New cable designs are also being developed to optimize underwater transmission. Coaxial cable designs with liquid dielectric insulation fluids have shown potential for better high-voltage performance compared to traditional oil-filled cables. Scientists are also experimenting with cables that include built-in pumping systems to actively cool the cable and further reduce losses.

There is also ongoing work on advanced power electronics to enable multi-terminal HVDC networks. This technology would allowmultiple connections between AC and DC grids, improving the flexibility and efficiency of underwater grids. However, more testing is needed to ensure reliability and cost-effectiveness.

While there are still challenges to overcome, scientists and engineers continue to make advancements in underwater electricity transmission. With further research and innovation, we may one day be able to transmit power around the globe through interconnected underwater grids.


In summary, the distance electricity can travel through water depends on several key factors. These include the voltage of the electrical source, the conductivity of the water, and the amount of dissolved salts and contaminants. Higher voltage allows electricity to travel farther, while pure water has high resistance and limits transmission distance. Water with more dissolved ions conducts better and permits electrons to flow further.

Through controlled experiments, researchers have measured electricity traversing over a mile in salty ocean water. In freshwater lakes and rivers, transmission length is much shorter at around 100-200 feet. There are still gaps in understanding exactly how far current propagates in different natural environments.

While electricity’s reach in water can be impressive under certain conditions, it also poses risks. Any time humans encounter electrified water, extreme caution should be exercised. Future work improving physics models and establishing safety guidelines will ensure the wise application of electricity through water.

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